There's a recent blog about it here https://world.optimizely.com/blogs/martin-ottosen/dates/2022/6/deploying-your-cms-12-upgrade-on-dxp/
But esentially it just spins up a whole new DXP Pass instance with it's only environments based around Linux Docker containers. You'll get new keys for sendgrid, deployment api, search and navigation indexes and such. It's essentially like starting and get a brand new DXP instance. Then you have to upgrade your code to CMS 12 / Commerce 14 and then deploy it as standard deployment API packages. When ready to go live the domains can be switched over to the new instances.
Hello all, I am seeing the Project Migration step on DXP portal and curious how does it migrate the solution to recent 12th version of CMS. Has anyone came across this step and run it? What are the notes those I should keep ready with myself before migrating my solution to 12?