2 things to make this easier:
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No need to manage domain, hosting providers. Just get privacy-first mail provider (like Proton or something).
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No need to big-bang it. Just start connecting new accounts to the new email instead of Googles. Then once in while change them for existing services (retail for example and government) one by one.
Then after 2 years or so you will notice a couple of old ones are from obsolete services or can be changed to finish it off.