What streaming sources support the latest DNAS these days? Last time I looked support for it was pretty limited. Has this changed at all in the last year?

the v2 DNAS takes anything which can provide a v1 and v2 style source. so it really shouldn't matter much on what the sources can do (other than limitation of features if it only works in v1 mode) and the main thing is using a v2 based source allows for using the multi-source support in the DNAS in a simple way via the same port instead of having to setup multiple ports to accept v1 based sources (which was new to v2.2.x).