iirc there used to be a Google snippet that did online checksum verification. it worked pretty well , but I did not let it run the tests of the extension, so it may not be 100% , I just used it for a quick check if there were other problems visible.
but i wanted to confirm with someone - my easiest options for online verifying checksums would be to trigger pg_basebackup then check pg_stat_database, or to install michael's utility?
Your easiest option is to just use pgbackrest, which verifies checksums as part of its process. So you are guaranteed to have every page verified at least as often as every full backup.
