Have you read The Metropolitan Man? I don't know what's your policy on fanfiction but it's a "realistic" take on Superman arriving in the 30s.
Haven’t read that one - looking over it briefly it seems pretty damn depressing, though I suppose that’s kind of the point. I’ll probably check it out sometime.
I’m definitely down for fanfiction, but there’s precious little with Superman I’m into - when I occasionally think of Superman fanfic I hope “cool, maybe there’s finally some cool cosmic adventure stuff in here given the comics so rarely go there, or some really insightful character observations of the kind writers too sparsely touch on!” and then it ends up being 7000 pages on a powerless high-school aged Clark’s torrid affair with Jason Todd behind Congorilla’s back or something. But keeping my eyes open, there’ve definitely been some over the years that worked for me:
* All In A Day’s Work: Good chance you saw this floating around on Tumblr awhile back, this is another really great little short comic by Tom Gimlin and Marcellis Wentz, on the weight of the job.
* Superman’s Story: Opposite Number: An excellent short piece by @spectralspices based on an idea he was nice enough to bounce off me, as Superman goes up against a pair of challenges unusual even for him - one comedic, one very much not.
* Pop-Drama: Superman: I don’t know how much this really qualifies as fanfic in the traditional sense - it’s a broad story proposal by @andrewhickeywriter on an ‘end point’ for Superman - but it’s damn fun and satisfying. There’s also a follow-up article where he elaborates on a major plot point.
* Superman Lives: Another short comic, this time by Joe Otis Costello and Des Taylor, where the Superman of 1938 is beamed in a fight with Brainiac into the world of 2014, and Lois Lane naturally gets the exclusive interview with the returned hero, the story being presented in magazine format. The characterizations may or may not work for you - parts do for me, others not - but it’s an interesting exercise nonetheless, and Des Taylor’s work is absolutely gorgeous.
* @ck1blogs: Clark Kent’s reasonably infamous Twitter account. He is not good at the internet, or humans.
* @filmcriticsuperman: Less well-known than its cousin ck1, which is a shame; unlike most “Film Critic X” feeds, it’s actually…well, really good, courtesy of @charlotteofoz. It maintains the voice throughout and perfectly, and while half the feed is indeed movie reviews - always through the filter of Superman - the other half is just Superman talking about his day, and while it was coming out it was probably the best ongoing Superman material of the last several years. If starting at the beginning of the feed to get a feel for it seems too ominous, worth it though it may be, a good sample would be the more traditional short story she did connected to it, a Superman Halloween spooktacular by the name of Yellowfire.
* Kosmograd Blues: A short story by The Quantum Thief and Invisible Planets author Hannu Rajaniemi focused on a Russian Superman analog, it’s a beautifully written, somber story of a superman who’s long since lost what made his own life worthwhile, but knows he still has a job to do. This was to be one part of a series of superhero short stories set in a larger world he had built - he wrote a little more about the details of it once - but to my knowledge this was all that ever came out of it.
* Kahlil: An ongoing webcomic by Kumail Rizvi in which the last son of Krypton landed in Karachi; it’s been awhile since I last checked in on it, but I recall it being very good, with some spectacular artwork making the few moments thus far of super-ness really pop.
* Superman vs. The Universe: A spiritual cousin to Joe Keatinge’s Strange Visitor, this is the story of an all-powerful Superman at the end of time looking back on his existence as he prepares for his last duty; the prose is stilted in places, but there are enough great ideas and emotional moments in here to make it more than worth your time.
* Repairing The World: I’ll admit some bias up front since the author’s a friend of mine, but starlightify’s DCU series of fanfics - largely centered around Superman and Batman - are a lot of fun, very funny and heartfelt. Some good samplers with Superman would be Salutation and Canidae.
* Silver Age Superman: I’ve never gotten my hands on this semi-legendary bootleg 1990 comic by Ed Pinsent and Mark Robinson, but the likes of Al Ewing and phenomenal comics critic Colin Smith have both declared this comic - starring by my understanding perhaps the most alienated version of its title character ever - among their absolute favorite Superman stories, and their word is more than good enough for me; if you see it out in the wild, I’d absolutely say pick it up. And grab a copy for me, would ya?
* Luthor’s Gift/Starwinds Howl: Bizarre as it is to list any Superman work of Elliot S! Maggin’s as fanfiction when he’s one of the characters’ most beloved writers, I suppose that is what these two stories count as given that they’ve only ever been published online and maybe in a fanzine or two to my knowledge rather than with DC’s official sanction, and they’re absolutely of a piece with his novels Last Son of Krypton and Miracle Monday. The latter is his take on how Krypto arrived on Earth; the former shows how Superman finally left Earth around the end of the 21st century the way he often hinted at in his other works.
* Tales of Smallville: Near as I can tell, I’m the only person on the face of the Earth - other than maybe Elliot Maggin, who endorsed these stories himself - who’s aware that on the site supermanthrutheages, Samuel Hawkins posted a series of 4 Superboy stories; him revealing himself to the world, his first big adventure with the Legion of Superheroes, a memorable dinner with a guest, and Martha Kent on her deathbed. On these stories, I know two things. 1. Posterity will unquestionably not validate him. It’s a handful of Silver/Bronze-Age Superboy fanfics on an out-of-the-way fansite, no one will remember them. And 2. He is a Morrison/Ennis/Maggin-tier Superman writer. If I have ever written anything in my life on Superman that you’ve agreed on, for the love of god at least read Martha’s Story, it might honestly be my favorite Superman story other than All-Star.
So along with those recommendations, I do have to throw a request on top: I vaguely recall having once read a short story somewhere online years ago about a Superman-type hero found in a field as an infant by farmers - one’s an alcoholic and one sleeps around, but they clean up their acts for the sake of the kid. He grows up to become a superhero and occasionally fights a Lex Luthorish scientist with an appropriately alliterative name who accuses him of impeding societal progress. Eventually, the hero flies off into space once everyone he knows dies, returning occasionally to Earth as he feels drawn back, to defend it, or rule it, or just wander it in obscurity; his longest and last stay is when he falls in love with a woman who he meets at a restaurant, when she’s the first in all those thousands of years to make apple pie as good as his mother’s. Eventually, he lives to the end of the universe, where he finds himself rocketing back through time and de-aging, crash-landing in a field and completing the time-loop. If anyone could point me in a direction towards it, it’d be very much appreciated; I don’t even recall if it’s any good, but I’ve been trying to find it for years and it’s the principle of the thing at this point.