I currently have a Steam Deck and am interested in horror games specifically (preferably survival horror with weapons but any is acceptable).
I have played some of the "playstation x" genre games on 8bit.io (modern games created with 8 bit graphics) and am interested in these type especially.
I have already played through the silent hill series, resident evil.
Honestly, I think a lot of people have hit the big ones already. Not being much of a horror gamer myself, I would throw Metroid Fusion into the mix as a sci-fi horror game. There's also a horror jankfest called Martian Gothic, which is on PC & PS1, which is interesting for the multiple characters working together through the game - but if they meet, game over - it's by the same team as Dreamweb. There's also Deep Fear for Sega Saturn, which is basically Sega doing Resident Evil, but underwater - I've only ever seen LPs of it, but it looks like fun - I don't know if you need a translation patch. You could try another contemporary game, Fatal Frame, which I played a demo of, where you use a camera to fend off ghosts.
Samus is alone on a space station full of X Parasites, a thing that nearly killed her (and later you'll find out some other stuff about them). She had to have her power suit surgically removed from her body, and her appearance was radically changed. When you go aboard the station, you hope to find survivors - in vain, of course. And through it all, the only "friendly" voice you have is a computer which Samus named Adam, after Adam Malkovich, her former CO.
You're alone. You're trapped with things that very definitely want to kill you, and I don't mean like the Metroids that just want to eat and grow. The X want Samus dead, personally.
Sure, it's a colorful GBA game built on the same engine as Wario Land 4. That doesn't take away the horror when some of the plot beats hit.