Note that I'm not suggesting you use any for-profit company's hosted git product.
Note that I'm not suggesting you use any for-profit company's hosted git product.
ETA: Many forges reintroduce the latter (commenting directly on lines of code), in which case this may not be an advantage depending on if such a forge is used. (But then you're back to using a forge, and needing to open the website to review changes in addition to using git and email.)
It is, however, also functionally equivalent to a pull request, excepting again the need for write-access.
It sounds to me, and I mean this quite objectively, not as a personal insult, that you're attracted to the email-based flow not because it is better, but because you just don't want to use a web UI. So since you define web UI as bad, you of course reach the conclusion that the email-based flow is better.
We can quibble about which is more convenient (admittedly I find the former better in this regard, although I recognize that this is a minority opinion), but they are IMO both more-or-less equally viable choices.