I don't think there is a qiime 2 plug-in to do this (yet!), but I have done it with ASVs outside of Qiime and it works great. If you know R, I would recommend the picante package for this job (picante PDF).
Yes! It works great... with the usual caveat that the ITS trees are imperfect.
(I would argue that NTI is one of the best things you can do with a ITS tree, as the accuracy of local phylogeny should be pretty good.)
Here's the paper where I use NTI and βNTI on both 16S and ITS data.
Colin