I am curious as to whether or not I can play Sea of Thieves on PC the same time someone is playing (For example) Fallout 76 on the same Microsoft account without logging the other person out.
I don’t see why not unless you’re both playing online
I don't think so. It's not possible to use a single xbox account on different consoles (Same generation) at the same time (if both are online). Considering both of the games listed are only online, I'd say no it's not possible. But maybe it counts windows 10 as something different and not another console. The best way to know is to just try it