In the Windows 11 Insider Preview Build 22557 release announcement of Microsoft blog, for the initial device installation of Windows 11 pro, internet connect and Microsoft account for sign in are required.
Microsoft BlogSimilar to Windows 11 Home edition, Windows 11 Pro edition now requires internet connectivity during the initial device setup (OOBE) only. If you choose to setup device for personal use, MSA will be required for setup as well. You can expect Microsoft Account to be required in subsequent WIP flights.
Users who often skip the Microsoft account setting during the installation or update process, may feel frustrated. As I usually log in to my Microsoft account only when I need to use the certain service such as Teams, Skype, Microsoft Store, etc. But later, this is impossible any more. But it is not strange since Microsoft has been pushing to register Microsoft account since Windows 10.
Anyway, we can wait for the final release to expect if there is anything be changed.