Hello all, thank you very much for the feedback provided. Given this feature has been a long time in the making, it seems to be the right time to release it. I am planning to do it still this week unless something unforeseen comes up, e.g. a new bug, or another release taking priority (e.g. a distutils update).
I think releasing it would be important to start collecting feedback from the broader community.
Regarding the compat mode, I reiterate that I have no strong feelings against keeping it permanently in the implementation, if we have compelling arguments and the buy in of the other maintainers. We have some time to discuss this in detail after we publish the release (which will also be good, since people that might not follow Python discourse will also have the opportunity to report use cases that might not be supported).