murena should emphasize much more an easy to migrate from old to new phone …
I agree, but this happened in a sense for Seedvault: for A14 and up they no longer interfere with upstream (and ship an old Seedvault version), but give you what Lineage updated to. They didn’t backport to A13 though afaik, but that is also due to how SV gets developed - older branches are not maintained.
There’s no other foss app that hooks into Android facilities for backup like Seedvault.