The longer you leave it, the harder it will be - a few have done the migration recently and documented it:
- https://forum.ghost.org/t/how-to-upgrade-to-mysql-8/
- https://forum.ghost.org/t/how-to-migrate-from-mariadb-10-to-mysql-8
- https://forum.ghost.org/t/debian-stable-upgrade-mariadb-to-mysql8
I’ve done it on a couple of dev servers, and four production servers that have a mix of fifteen Ghost blogs, and some other software that also uses the database.
Do it on a test box first - and take an initial backup / snapshot of everything, follow the instructions, take notes and write up your experience
