you dont need to do much, i would say my time budget on self hosted replicated and backed up MySQL database administration is under 20 hours per year. yes the first couple years took more time (learning, building out a backup strategy) but id have the same amount of learning with a hosted solution so i don't consider that part of time spent.
I felt like generally you have nothing to do, except sometimes you gotta do something like respond to disk quota alert and stuff