I really don't want to make a Microsoft account but many job interviews are held on Teams. I see that there is a web client which I will definitely use instead of the unofficial Flatpak for Linux.
If I create a Microsoft account with one of my privacy friendly emails (custom domain), would Microsoft start to receive the emails that that account receives? If so, would you suggest that I make a burner Microsoft account for this specific use case?
I just setup a new Windows 10 VM this morning and it was the first time I was not able to skip making a Microsoft account. So I just used an email alias and then instantly paused the email address after receiving the verification code. Regarding your uncertainty around what seems to be Microsoft having access to the email inbox somehow, I can't see how that'd be possible unless the email is maintained by them or you decided to use Outlook. Use a burner email and make sure it's only provided for the Teams account and you'll be in a much better place than most Teams users.
I believe you can skip account registration if you kill the internet connection to your VM while running the installation.