One interesting thing about Barman is that it just uses PG's own backup utilities. It doesn't implement custom parsers and things like that. So, there's less maintenance work needed for Barman when PostgreSQL changes data-file internals. Tradeoff is that there's less custom optimization than pgBackRest/pg_probackup/WAL-G-local.

Databasus seems to be taking somewhat similar approach to Barman, but (at this time) does not appear to use pg_receivewal, which makes it less efficient than Barman.

For PG v17+, Barman seems to be the most efficient backup solution based on PG native tools, that is able to do low-RPO or even zero-RPO (if configured as a synchronous receiver).