Supabase developer here. It shouldn't (and doesn't) take a week to migrate 40GB, I'm sure most of that time was strategizing, analyzing, and testing things. Supabase is pure Postgres running on AWS, so migrations are pretty straightforward. Things mostly depend on where you're migrating to/from, and the network latency between the source and destination. 40GB should take minutes in most cases.
Supabase developer here. We're big fans of Pocketbase here and love the stuff they're doing. I did some work with it early on and it's great, but since I'm not a Go developer, I found the customization options pretty lacking. I wish they'd develop a way to write custom code in Typescript or some other way to write custom database functions. I'm excited to see what's in store for the future of Pocketbase (as I've always been a fan of Sqlite and it's compactness and simplicity.)
A LOT! Probably most.
But Supabase is committed to the free tier and it's not going anywhere. It's crucial to helping demonstrate all the features and the DX to developers.