New to Azure and wanted to get thoughts on my situation.

Recently joined an organisation that have no on-prem AD. They deploy laptops and desktops to end users with local accounts. These devices appear in AAD as "AD registered".

AAD has multiple verified domains, however default domain is still company.onmicrosoft.com.

Microsoft365 being used and licenses are currently business standard (no Intune)and email address is company.co.uk, which is one of the verified domains.

I would like to get in a position whereby, we can join all machines to company.co.uk domain. I think I need to change the default domain to be company.co.uk but am concerned on the impact on the rest of the infrastructure (various VM's, Storage accounts,.etc, etc.

I guess a good test would be to see if I can join a machine to the company.onmicrosoft.com domain? If so how would I be able to do this?

Also I'm hoping by these machines joining the company.co.uk, I should be able to increase control of devices (at least until we decide to get Intune)

Any thoughts would be appreciated