I think a recent version of Windows I had the misfortune of setting up also required a Ms account: no option for a local install. It's also possible that I'm just stupid and didn't see it, but (shrug)
The secret is you have to install Windows 10 with the network disconnected. If it doesn't detect a network connection, it lets you create a local account
You can bypass it by either turning off the network connection prior to a new/clean installation on 20H2/21H1. If you are stuck on the account screen during the installation process, then entering wrong credentials 3 times will present you with a local account option. However, if you have completed installation, then there is an option to turn it into a local account in Settings --> User Accounts --> Change your account type.
It should, even on the latest Window 10 builds, but only if your computer is not connected to the Internet...