The Microsoft technician told me to completely reinstall the PC with Windows 10 using the original Windows 10 serial number or to buy a Windows 11 serial number in the store.
That's a terrible answer; however, I do not know the upgrade path from Windows 10 Pro to Windows 11 Pro. Is that free? If so, reinstalling Windows 11 Pro "should" be assigned to your Microsoft account. Once you login with your account, the Digital License kicks in. (Yeah, all that is "supposed" to happen)
I went from OEM Windows 11 Home, purchased $99.00 Pro, from Microsoft on 21AUG2023. Everything went smoothly until the day I updated the BIOS 03OCT2023.