When I created a new google workspace account I wanted to move my personal project to inside the new organisation.
It's a pretty simple process, you just need to add the correct permissions to the organisation and then you can migrate the account over.
In the new organisation
Assign to your personal google account Project Creator role on the new Organization. Make sure that you are in the organisation and not a project, otherwise your won't see the role.
In the personal account
On the project you are migrating (not the organisation this time), assign to your account the Project Mover role.
Then you can go to Manage Resources
Then use the menu to select migrate