Oddly enough, I had the simplest experience of installing Windows 11 25H2 on a new ThinkPad just recently. Apparently the Windows ISO doesn't have the WiFi drivers for that specific machine out of the box, so during setup when it couldn't find an internet connection, it simply offered to create a local account.

So I would assume, if there is a way you can temporarily disable networking (e.g. in BIOS), then that would be the easiest way to avoid creating a Microsoft account.