This is the correct answer. Dell, and other oems, have stored their windows keys in firmware on motherboards for years now. You could literally install on a fresh drive and it should auto activate. Typically at most you have to go to click activate yourself.
This is all assuming the machine came with a pro license and wasn’t upgraded of course. It should have a sticker on it.
Pretty sure something like 10 years ago crashplan deleted a bunch of customer data in a deduplication job gone wrong.