BWW has a tubeless rim-brake wheelset that comes in 26
https://bicyclewheelwarehouse.com/St...wheel-set.html . I just got one for my own build. The wheels seem light, look nice, and a 26x2.3 tire seated no problem on them. I still haven't taken them for a ride yet but I'm stoked on it. Probably getting a donor bike would've been an easier and cheaper way to get this build rolling, but I wanted to try out some new components on it, like a wide cassette and clutch derailleur. Wheel see if it pays off!