Backfill bgworker Extension?

One of our challenges we have is that our engineers have written frameworks
to backfill data in several different DSLs, and every time they adopt a new
language, they maybe need to write another one.

To be clear, what I mean is batch updating a large set of data in small
pieces so as to avoid things like lock contention and replication lags.
Sometimes these have a driving table that has the source data to update in
a destination table based on a key column, but sometimes it is something
like setting just a single specific value for a huge table.

I would love instead to have a Postgres extension that uses postgres
background workers to accomplish this, especially if it were part of core.
Before I venture into exploring writing something like this as an
extension, would this ever be considered something appropriate as an
extension in Postgres core? Would that be appropriate?

Thanks,
Jeremy