Es gibt von Nager IT faire Mäuse mit 2 bzw. 3 Tasten, vllt. ist das ja was: https://www.nager-it.de/maus/bestellung

Which DE are you talking about? It sounds like KDE/Plasma but you didn’t specify.

It’s a mixed bag. Personally I wouldn’t use a non-standard port.

Consider that port numbers under 1024 are Privileged Ports. You would either have to make sure that no other privileged service is running on the port you want to use for SSH when using another privileged port or you need to make sure that no unprivileged program tries to use the same port as your SSH service when using a non-privileged. Overall it adds a bit of overhead and possible headaches for barely any gain.

Fail2ban should work with a different port without any further configuration but it might not.

You would need to specify the new port when using ssh (using the -p$PORT option). Just keep in mind that security through obscurity is not considered secure in itself. You could instead consider a service like fail2ban that automatically blocks connections from certain sources depending on your set parameters.

What @StarkZarn said is correct. Just one more thing: Did you reload/restart the sshd service after changing the configuration? If so you should be good.