Build your dad a Lack arcade. You can set the pizero for read only so powering off is easy or use a simple command in the config file: dtoverlay=gpio-shutdown,active_low=0 and he can have a switch to power the unit off or hit an admin button wired to the Gpio pin 5 and 6 I believe. The pizero is not powerful enough for arcade gaming, maybe Atari 2600 type games or NES but that is it. Get PI 2A for $25 or a 3B. Target has them on clearance. But if you have to and use the pizero there is a dedicated image from CASTLE on a site I cannot mention due to Rule 5, that works great running retropie and all you need to do is have it open on favorites or FBA on start.
My brother is the same, very technical intolerant, I made him a Lack table, and it surprisingly is still in his house. You want something simple and accessible for casual play, but is not complicated or looks complicated.
Make sure the table is bland in color like a black or white depending of his home decor.
You might need a demo Lack table for getting the cutting right. I got a $5 4:3 TV which solved a bunch of problems for sound.
But you are a veteran BYOAC'er. You got this.