I have a passport.com email account. Can I make it my primary alias?

No, sorry, passport.com addresses cannot be set as the default – they can only be used for incoming mail. This has been the policy since they moved the accounts to Office 365 servers. — Diane Poremsky M365 MVP, specializing in Outlook, Exchange, and Microsoft 365 apps.

https://answers.microsoft.com/en-us/outlook_com/forum/all/i-have-a-passportcom-email-account-can-i-make-it/c49c4942-4377-41b4-9cb9-6d80e0b8c04b