> when our whole team is focused on one set of interrelated new features, we spend a lot of overhead coordination time figuring out how to not create conflicts for eachother. So we can work in parallel, but not in real-time with eachother's changes

If multiple people work on the same code (interrelated new features) at the same time, it seems to me they would have to sequence their work (i.e. coordinate) so as to not step on each others' toes. Put differently, this sounds like the problem is inherent and won't be solved by technology.