US would like to provide assistance, but they feel there is no reliable partner. NUG is quite indecisive, and ideological differences in NUG leaders leads to a lot of background infighting. Some NUG members have allegiances wirh China somehow despite China supporting the junta. Ethnic armed groups have a history of not getting along with each other and also have a lot of factional problems. It can be a bit like game of thrones.

If NUG was willing to cooperate and accept help offered, you'd likely see a lot more tangible assistance coming to them.

USA wouldn't mind pulling Russian resources away from Ukraine by supporting the democratic uprising, and having a pro-west country next to China would be very good for their regional goals. This time is probably the best opportunity for democratic forces to get assistance, but all they do is waffle.