I too bought aftermarket batteries because I purchased the groupset without them. I am now at roughly 9000 shifts according to the app (although I'm not sure if this has been reset somewhere along the way when doing firmware updates). I've clocked around 1700km on this groupset and I've just charged it for the second time like 100km ago. So I think it's roughly on par with Sram AXS groups when it comes to batter life.

What is slightly annoying is that while the battery level is correctly displayed in the app, I still get a low battery level warning every time the groupset connects to my Wahoo when starting a ride. It's a bug that apparently still hasn't been fixed. Unless one of you guys knows something I don't?