GPOs just edit the windows register so you could just apply all the changes using regedit instead of using a GPO.

No. Because GPO involves differing rights as well as registry hacks, and because GPO allows you to change certain settings that are not in the registry at all, there are some things you can literally ONLY do via GPO. It’s been a while, but I’ve spent multiple hours trying on a few occasions when the situation demanded it, and ended up either installing Pro with GPO or abandoning the effort altogether.