Looking for a realistic survival game...

The long dark without hesitation :)

I'll add another vote for Subnautica. One of the best gaming experiences I've had. Heavier on the environment than the survival (survival's pretty trivial after the first hour).

The Long Dark is great, as long as you don't care about the story mode. I haven't followed it since they released it, but I remember it being really bad at release (the story mode). Challenges and Survival are really fun.

Try Project Zomboid

Life

Realism, you say? Try UnReal World

Kappa

https://store.steampowered.com/app/248860/NEO_Scavenger/ Definitely this one, it has all aspects you're asking for. There are some monsters, but it doesn't ruin the realistic near-future post-apocalyptic feeling the game has.

Since they are both in my wishlist and nobody still recommended them, I can suggest you two survival games to check: Judgment: Apocalypse Survival Simulation (even if there're demons and monsters in it) and Bermuda - Lost Survival: it's still in EA but it's like Raft with a more realistic graphic.