Anything by Stanislaw Lem. I really liked Fiasco.

Read the other books in the three body problem series! The story is wild.

Iain M. Banks.

Roadside Picnic by Arkady and Boris Strugatsky. Inspired the STALKER video games.

At some point in the 20th century, aliens esentially fired some rockets filled with garbage at the earth. The fallout of these rockets created several “exclusion zones” around earth. The book chiefly follows speculators who risk crossing military cordons in order to recover and sell salvaged tech.

Check out Roadside Picnic, inspiration for the S.T.A.L.K.E.R series.

Another person already said Stanislaw Lem, so I'm going to take a side route and suggest one of my favorite series...

BUUUT... It's not sci fi. It's still genre fiction, but rather modern dark fantasy.

The Night Watch books by Sergei Lukyanenko

https://en.m.wikipedia.org/wiki/Night_Watch_(Lukyanenko_novel)

Premise is that magicians, wizards, vampires, witches, werewolves, sorceresses, they're all real. The forces of light and dark were at war for centuries before they came to an agreement. The forces of dark would limit their activities to licensed behaviors, policed by the Night Watch, and similarly the forces of light would restrict themselves, policed by the Day Watch.

Now, here's the problem... Lukyanenko is a Russian nationalist of Ukranian heritage. He fully supports the war in Ukraine.

The books have nothing to do with it and were largely written even before the Crimea invasion, but since then Lukyanenko has made a large number of unfortunate comments.

So how much you enjoy the works is going to depend on how much you can separate them from the author. ☹️

Not Before Sundown by Johanna Sinisalo.

Metro 2033 by Dmitry Glukhovsky.

Like others, I'm hyping the Strugatsky brothers' Roadside Picnic, and Stanislaw Lem's Solaris.

With the caveat that I don't really like his books, The Sands of Sarasvati by Risto Isomäki.

Twenty Thousand Leagues Under the Seas by Jules Verne is absolutely worth the read. Just bear through the long lists of fish.

Tarkovsky movies, either Stalker or Solaris. Both are incredibly slow but very solid. Admittedly, I watched them both during pandemic so the length bothered me less than it might of.

If you’re interested in in humorous sci-fi, then check out The Hitchhiker’s Guide to the Galaxy.

I'll suggest The Doomed City by the Strutgatsky brothers. I found it much more satisfying than Roadside Picnic. It's much longer and much more philosophical. My username is from one of the characters in the book!

I'll interpret non-US a bit broader as non-English. English is hugely dominant in scifi so it's often hard to find good books in other languages. I'd also love to hear the recommendations of others too! A few I read:

• (German)
  • "Die Welten der Skiir" trilogy (by Dirk van den Boom): https://bookwyrm.social/book/593373/s/die-welten-der-skiir-1 is really great . He also wrote another trilogy (Die Reise der Scythe) which is also quite nice.
  • "3517 Anno Domini: Wir waren Götter" by Raik Thorstad. Note that his is a primarily an M/M romance, but it has a nice dystopian scifi setting.
• (Spanish)
  • "En un lugar llamado tierra" - I read this long ago, don't remember much: https://bookwyrm.social/book/979935/s/en-un-lugar-llamado-tierra
  • La señal - https://bookwyrm.social/book/979918/s/la-senal
• (French) The works by Jules Verne should probably be mentioned here, despite being written well a century ago. "Vingt mille lieues sous les mers", as already mentioned in another comment, is a must-read classic.
  • "Helstrid" - I have this one on my e-reader for a while but haven't properly started it yet: https://bookwyrm.social/book/1289177/s/helstrid , so I can't say if it's any good.
• (Dutch) Long ago as a teen I once read "Coriolis, de stormplaneet" and liked it: https://bookwyrm.social/book/979934/s/coriolis-de-stormplaneet

We by Yevgeny Zamyatin.

Anything by the Strugatsky brothers.

Andreas Eschbach is quite unknown outside of the German speaking world, but I can recommend e. g. his The Carpet Makers. It's more of a soft sci-fi, dealing with a society on one quite strange world.

One of the most complex soviet scifi author is Ivan Efremov, i can recommend The bull's hour

I recommend Ken Liu's translated Chinese scifi short story anthologies, which include some stori3s by Liu Cixin. The books are called "Invisible Planets" and "Broken Stars".

I really enjoyed Lord of all Things by Andreas Eschbach, a German author. Available in English

• Memory of Water
• Jean le Flambeur series

The Best of World SF is undeniably an excellent sampler of voices from around the world, both of authors and of translators.

The editor comes off as maybe a bit self-centred? But I can't deny they have excellent taste and connections.