@mnazzaro have you seen fly.io's new sprites.dev offering?

I have! It's pretty interesting and handles a lot of the problems discussed here, but is a little young for us. For one thing, it doesn't have fly replay, so we'd have to build a separate proxy again.

If we were starting from 0, I would definitely try it. My favorite thing about it is the progressive checkpointing- you can snapshot file system deltas and store them at s3 prices. Cool stuff!