https://watabou.itch.io/one-page-dungeon

It kind of only makes one style of dungeon (as far as layout) but it's still a good tool, especially if you need to generate something on short notice. When I've used these, I typically ignore most of the notes it puts in and populate it myself for something more coherent.

Maybe not quite what OP had in mind, but I'm a huge fan of characters that are simple enough to be quickly recorded on just a sheet of notebook paper. Stuff like Maze Rats, Knave, or even some PbtA games. There's something that feels nice about not needing a special layout to surface just the "important parts."

I've just started playing in a 2e campaign over Discord. First time playing (as in being a player rather than DM) an old AD&D, so that will be an interesting experience.

I've been running playtest sessions of my homebrew system and touching up the language there, so that's honestly taking up way more brain space right now.

That's a good idea, I should've considered looking at real world examples as well