Actually, a while back, I had figured out a way to change mysql to mariadb. It was ugly and kludgey, but the couple of times I tried it, it worked. Mariadb is truly a drop-in replacement, from the new tests I have done. I'm not a DBA, but it works underneath things like Nagios...
I have a question (two, actually). I changed $HOME/.config/akonadi/akonadiserverrc to be QMYSQL rather than QSQLITE3. However, when I try to restart akonadi, I get the same startup messages...
Mysql server executable/server/configuration not tested