best travel to taiwan
i just did SFO-TPE on EVA J and TPE-NRT-SFO on NH J and UA F. I believe one way UA F ticket cost same as many miles as BR J (BR J cost 10k more miles than UA J). I think the BR flight being nonstop TPAC makes more sense. The stop in NRT reduces the TPAC flight time and limits how long one can sleep on board.
You can book partner flights with your UA miles on united.com (but you may not see all of them, not sure if some level of blocking is still happening).