Looking for additional info on Gamepass and setting up the console with kids

Yo! I'm a total xbox noob so I appreciate any real-world info you can provide. Possibly looking at grabbing an xbox for the house, intended use mainly for my kids (8-9).

Primarily considering xbox over rivals because of the gamepass. I hear it can also be used on computers, is that right? Would like to have it on my PC as well if possible buy only buy it one time.

Next, kids accounts. Is it easy to attach to my microsoft account and set up kids under mine? No experience at all with this, and would love input from others who have this set up. Don't need my kids exposed to the nasty world of global chat yet lol.

Thanks for the help!