All services have been migrated, now including the podcast. It was stressful, because Castopod has zero such documentation. I started with Dokuwiki (files and folders), then worked my way through migrating Flarum from MySQL to MariaDB. Spun up some new services via PostgreSQL and SQlite. Flarum at least gave me the experience of gaining some foundational understanding needed to then migrate Castopod via mysqldump, adjusting permissions, rewriting .htaccess to redirect to a simple migration.html page and eventually flip DNS after carefully adjust cron and tasks:list expected by php spark for Castopod.

Because it is always federating, with no supported method of disabling, I was terrified of it breaking. Obviously, it still could... but, it seems to be working.

Will this migration become a episode?

I'm curious what your current architecture is.

Absolutely. Open to thoughts on it, because it is a lot. Was learning about systemctl --user space after reading comments that "people running containers probably don't know the first thing about their database."