Genuine question: I've been hearing good things about PopOS.
How realistic is it as a windows replacement ?
If you mean just replacing Windows with Linux in general: it's great, unless you need to run, say, Adobe Photoshop, Microsoft Excel, or Fortnite.
There's no way to use Wine for Microsoft Excel?
There were attempts to auto configure apps, like bottles program. This did work quite well when I used it for simple programs.
As with Linux. It takes some time to get familiar. Once you set up everything correctly, it will just work.
Biggest issue is printer drivers, I'd say.