Earlier quoted context omitted.
Dokku is also nice and battle-tested: https://dokku.com/ And may I also plug Lunni, a self-hosted Docker Swarm-based PaaS I'm working on right now: https://lunni.dev/ Both work pretty well on $5 servers.
Lunni looks really interesting! Looks like a Coolify competitor, I'll definitely check it out. Do you have a Discord to join? Coolify has one and I found it great to discuss the project and talk directly to the creator. I used to use Dokku but I personally liked the GUI from Coolify so I've been using that. Nice to see that you have a GUI as well, makes configuring apps a lot easier.
(Bridged to Matrix: https://matrix.to/#/#lunni:matrix.org)
Lunni is actually pretty young in terms of community (just me and a few friends now :-), so just a room in Telegram was sufficient so far, but I think it's a good time to start something more official.