Hi u/Money-Natural7797
There are loads of devices to choose for all price ranges really, such as this device from Anbernic:
If you dad is into keyboard based 80s gaming though, one issue where this is going to fall down is in keyboard support, as its only going to play games that used the controller well.
What sort of stuff was he into? Another option you could maybe think about is the commodore 64 mini, which was released a couple of years ago. You can add any c64 to it, and I believe it can also emulate Amiga and (probably) Amstrad.
Happy to discuss further!