I'm curious what you use for a database on Fly.io. When I last looked into it, a proper managed database option was the last thing that they were missing from what I wanted.
Their “you’re on your own” option is really nice though for cheap, non-mission-critical stuff, and you can even scale the compute to zero during inactivity and just pay the attached volume costs.
None of those integrated of course, but easier than going big cloud or self hosted