

There does exist a tool that does it. The creator posted about it on the fediverse. It only supported ubuntu at the time but looked extremely promising.
I cannot remember it’s name. :/
Maybe it’s linixify? But I remember seeing a post on lemmy with a youtube demo?

Do you have a source or benchmarks for the last bullet point?
I am skeptical that optimizations like that wouldn’t already be implemented by postgres.
Edit: Btrfs has the worst performance for databases according to this benchmark.
https://www.dimoulis.net/posts/benchmark-of-postgresql-with-ext4-xfs-btrfs-zfs/