I'd personally recommend pgBackRest as a wal-g replacement. We (Covalent) started with wal-g ourselves, but pgBackRest does full backup and restore
so much faster. Besides the parallelism (which is great), pgBackRest's backups are manifests, symbolically mapping to the individual objects in storage that may have come from previous backups. Which means that a differential or incremental backup doesn't need to be "replayed after" a full backup, but instead is just like a git commit, pointing to some newer and some older objects.
Also, auto-expiry of no-longer-needed WAL segments (that we use due to our reliance on async hot standbys) along with previous backups is pretty great.
And we haven't even started taking advantage of pgBackRest's ability to do incremental restore — i.e. to converge a dataset already on disk, that may have fallen out of sync, with as few updates as possible. We're thinking we could use this to allow data science use-cases that would involve writing to a replica, by promoting the replica, allowing the writes, and then converging it back to an up-to-date replica after the fact.