I am assuming that the firmware includes Windows 10. But why should it? Normally when I upgrade the firmware on a PC, it is just a set of individual drivers and perhaps 100MB total and indeed Windows keeps some of them upgraded, at least on major brand PCs. On boutique PCs, I have to get the drivers from the hardware vendors. Still, what is in the firmware?
I updated my P2Max to Win 11. I used a USB drive created with the media creation tool, but it installed without any tricks – the P2Max met the Windows criteria for upgrading