Yeah, DigitalOcean's App Platform recently added support for custom images this year [1] (I was also waiting for that). I'm currently running a $5 droplet for my service [2] powered by docker-compose, but really looking forward to deleting some bash scripts and going all in on Render or Fly.io :)
[1]: https://www.digitalocean.com/blog/introducing-bring-your-own...