A month ago somebody was asking about how to properly route musical instruments into vrchat microphone input. I took another crack at it today and have what I think is a reasonably explainable setup for voicemeeter potato (which is essentially voicemeeter banana with more inputs). The main annoying thing is that voicemeeter has a very unintuitive signal flow. Once you get that A1 = hardware out, B1 = "VoiceMeeter Output" in windows input devices, and "VoiceMeeter Input" in windows output devices = "Voicemeeter VAIO" in voicemeeter's UI, it makes sense.

Note that this doesn't have a DAW involved, just windows and voicemeeter and a hardware analog input for the piano. If you want other plugins, soft synths, or sidechannel stuff, I think you need a more complicated thing with the "master section" part of the UI so you can route voicemeeter's input channels to ASIO input channels, and ASIO output channels back out to the right places. I'll try to recreate that setup tomorrow sometime and post a screenshot.

FWIW playing instruments with vrchat voice input is not ideal, as you're subject to its voice-specific gating and compression. Notably, sustained soft notes will get gated. However, there is another way to get high quality and reasonably low latency (1 second or so) audio into vrchat through RTSP streaming, which I'll also post about once I figure that out.