It's always bothered how much isekai writers insist on sticking to a fantasy setting- AND NOTHING ELSE

I can't be the only one that genuinely wants to see a sci-fi isekai

They do exist. I just forgot the names of those.

Yeah, especially because a significant number of isekai involve the protagonist not just going to a fantasy world, but specifically the world of a video game, so it's odd that they haven't at explored other common game genres at the minimum. The closest I can think of to scifi isekai are Dr. Stone, Futurama and parts of TRON, all of which technically fit but don't really feel like what you'd expect from a scifi isekai. Mmmaybe you could say Knights & Magic is one too since it has mecha, but the rest of the world is fantasy themed so personally I wouldn't count it.

Exactly! Though mecha in in a fantasy setting isnt anything new- escaflowne and rayearth come to mind (and surprise they're also isekai)

The closest examples of sci-fi isekai I could find were these anime:
1. Re:creators- though that falls more into a science fantasy reverse isekai (though now that that I think about it- they never did explain how characters were getting pulled into the real world
2. Revisions- though that was more of a time travel alternate future story
3. I guess the original digimon adventure kinda counts?