Mount a Windows 11 ISO. Open an administrative command window. Navigate to the new drive letter. Enter this command:
.\setup.exe /product server /auto upgrade /EULA accept /migratedrivers all /ShowOOBE none /Compat IgnoreWarning /Telemetry Disable
I’ve used this to upgrade 10 to 11 on non approved hardware, going back to at least 2nd Gen. Intel CPUs. I’ve used it to upgrade existing Pro, EDU and IOT that didn’t want to upgrade.
The install window will say server but it isn’t.