My hand joints are getting better finally and I wanna learn an instrument. The thing is, I'm dumb and have struggled really badly with reading music in the past.
You don’t need to learn finger combinations like on most brass and woodwinds, nor chords like piano and other string instruments. Just the 7 positions the slide can be at. Blow a raspberry and the note comes out.
Trumpet is similar but a lot easier to store and transport. Also those three valves are pretty much the same amongst other brass instruments like French horn, baritone, tuba, etc. so you can move between instruments if you choose.
If it's a short note, it's usually not that dramatic. If it's a long note and you're still playing it, then have no shame in adjusting as soon you hear that it's off.
Generally, though, don't beat yourself up about it while learning. Just make a mental note that you eyeballed too low/high and try to do better next time.