Unfortunately, no, it's not working. I use Rustdesk all the time. I've found a way, but it's really stupid. I have a GL.iNet Comet to manage my headless machine. That unit supports microphone passthrough. I send my mac's mic through that to ubuntu. It's an awful solution hah, but it works. I'm able to use dictation through that on Ubuntu. I didn't buy the comet specifically for mic use. I found out after the fact that it was able to do it.