by the lever being on the end of the handle bar , you shift while holding on..

one thing about the Bar end levers making them a Touring favorite, is simplicity..
Less to go wrong.. like Downtube levers.. [which you do take a hand off, to shift]

FWIW, Co Motion can build around a Rohloff hub. after 20 years of tours,
I went from a 7x3 derailleur drive train, to there..
they only use a 2 cable Grip Shifter.. there are workarounds for Drop bars..

then crankset matters less , just needs to use 1 chainring..
Lg wheel 39t with the 16t comes std on the hub.

with a 20" wheel , I use the 53t .. Bike Friday is across town from Co-Mo.