We've had a number of folks migrate over to Crunchy Bridge [1] from Heroku, the only main feature we're missing at this point is dataclips which is coming. We can also help with pretty much no downtime migration even for larger databases. And the team over here is pretty much same team that built the original Heroku Postgres.
One thing that I have really come to like with Heroku is the pipeline. fly.io doesn't have one (I don't think?) and render isn't the same; it rebuilds for different stages and there's no concept of 'promoting' the same slug.
