Hmm I cant get my head around the keyboard mouse situation. I doubt the magic keyboard/mouse will work. I can use a wired one no problem BUT is there something like I plug in 1 cable into either my mac mini or MBP and input devices and display switch?
There are software solutions like SynergyKM and ShareMouse that will sent keyboard and mouse input from one computer to another. Their intended use is where each computer has its own screen on your desk but you should be able to make it work.
The other software way to do it is Screen Sharing.
Depends what you have. Think Logitech can auto switch with some models.
Assume they’re both wireless devices? They should have the ability to connect to more than one device and switch with a button.
If not, you could use the monitor USB ports which sometimes act as a KM switch themselves.
It really depends on how often you think you’ll be switching.