Interesting, that was the second option I thought of way back when, but figured dealing with hardcoded positions would be finicky and annoying. I guess part of it is how much time and effort you're willing to put into replaying the level over and over to hand tweak it to what you like, maybe I just don't have the patience for that lol.
For sounds I normally use a variety of CC0 sources, freesound + sound packs + personally recorded foley and VO, and then I edit them in audacity. It's not as high quality as professional sound designers who can make some truly amazing stuff (idk how they do it frankly), but mixing and matching existing sounds, tweaking their levels and editing them (and building up a personal folio of sound effects over time) is a great way to get more passable sounds. I still have a long way to go though and I don't think my sound design is top notch, just middling to decent... It's definitely a weird grey area for a jam like this where you are 'supposed to make everything yourself', but imo an important part of sound design is repurposing a variety of sfx and it's not really reasonable to do that only with personal recordings made midjam??? Idk I'm rambling now.
Loved your game, thanks for the insight on your process!