Seems more similar to Hasura than to Firebase. Firebase adds functions, file storage, and authentication on top of the database. I didn’t see any of that mentioned on the site.
Hasura also some limited support for generated multi-table transactional APIs, which Postgrest doesn't. Meanwhile, Firebase supports arbitrary read-modify-write transactions.
This team has its work cut out for them and I can see a fierce competition with Hasura and Firebase.