He must be bored out of his brain in that LA mansion.
Absolutely, Fanny, for all the reasons you elucidate.
And, of course, the things that might have replaced seeing friends and family or his hobbies (although he's not allowed to hunt anymore, and I'm not sure if Meghan's given the green light to polo, in view of the alleged cruelty to the ponies on occasion), like red carpet events or addressing important meetings with his important thoughts, can't happen at present.
Apparently, he's been persuaded to give up drinking too (having been a bit of a party boy in his youth) so he can't even get pissed every now and then.
They haven't even got the day-to-day tasks of shopping for/cooking food, organising the house, WFH (properly, I mean; not just churning out the occasional publicity grabber). I read Meghan likes to cook. So do I, but I imagine it's even more fun if you don't have to do it, every day.
There's the rolling-around of course. Ooh! And yoga!
And maybe he'll catch up on his reading.