As for the missing visual notification telling me it is safe to remove a drive, it seems that I'm not the first person experiencing the problem: there's a long thread from 2018. It should be resolved now in theory. I also tried Ejecter (installing fails) and my-udev-notify which were recommended back then but my-udev-notify then only notifies me when the drive already was physically removed, not about whether it is safe to do so.