I built a bike last year (Covid project) and was considering Etap, because I could use a set of carbon bars I already had, and didn't have to worry about internal wiring. Couldn't find a groupset anywhere at the time, so I went with Di2 and aluminum bars designed for internal wiring.
I'm glad I did. SRAM has stopped all production of components for earlier 11 spd Etap systems (although now they have some updated software that will allow you to buy the newer 12 spd levers and reprogram them to work with 11 spd.) And now, with the new 12 sp Di2, there are no wires from the levers to run.