I just tried this out now with an email from my personal domain that I have configured to send via my gmail account. I got a 10/10, but DMARC does not seem to be required for this. It shows a yellow checkbox for me on this, the same as it shows for me not having an unsubscribe button, which hardly gives the impression of it being necessary, given that I would not expect an unsubscribe button to make sense for most people manually sending emails to their customers from corporate email accounts.