effects of nullifying bytea column on storage

Hi:
psql (11.5, server 11.3) on linux

I have a table with a bytea column which, of course, contains binary data.
After 60 days, I no longer need the binary data but want to retain the rest
of the record. Of course it's easy to just update the bytea column to null
for the older records. But I can almost imagine this record on disk with a
big "hole" in the middle where the bytea data used to be. Is there a PG
daemon (the vacuum ?) that will "heal the hole" in time?

Thanks !