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.
I wonder if that is something new in 25H2 then. My computer also does not have working network drivers out of the box and when I installed 24H2, it just gave me a screen to install the network driver from a flash drive. There was no way to skip or continue without it.
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.