For wildcards you need a Caddy build that includes the dns plugin for your specific provider. There's a tool called xcaddy that helps with that. It's still kinda annoying because now you need to manage the binary for yourself but when I tried it with Hetzner it worked fine.
it's funny because, obviously, they can't really advertise this and the torrent extension, but that seems to be the main way people are actually using it. so a lot of people end up trying stremio, and then voice (valid!) criticisms that in reality just don't apply to how people actually use stremio.
You should try it. I switched from Knex to Kysely since I was early in a project and Knex lost its lead developer (IIRC) and the typing Kysely gives you is extremely effortless and works very well.