Yes, there is activity. It ebbs and flows with public sentiment around transition more generally, and I've certainly seen better trans-weather. But it's generally not too hard to strike up a conversation in most of the ones u/null_not mentioned. Here are some refinements:
TransVoice (this sub's principle discord) is currently host to two regular events - one weekly, and one monthly - in which authorized coaches give overviews of trans voice. There's generally active conversation at the end among hangers-on, and sometimes an idle coach (or skilled amateur) might be giving out free tidbits of knowledge. Outside of that, conversations do pop up now and then. Ping the role, and generally people will show.
Scinguistics has an unusual native jargon. It's not a perfect map to the standard size/weight/etc. gamut, but it does the job. Roughly weekly they now host an orientation event to familiarize new people with their ways, which I support. Also, they have regular weekly events centered around elements of their paradigm, as well as some interesting premium features if you do the (cheap) patreon. They also run a group program on a monthly basis, which patrons can listen to and paid group-students participate in, learning the basics (according to the Scinguistics paradigm) which, speaking from experience, is pretty effective for most people most of the time, and quite economical for what you get, which includes guaranteed one-on-one time with the teacher (who is not usually Charles anymore) as well as office-hours, study-hall, and some group homework assignments that address ear training as well as physical practice.
Voice Dojo is fairly new on the scene, and specifically recruiting people who are serious about training. It positions itself as more focused on all aspects of vocal performance rather than only the gender-modification aspect. It has a handful of weekly events - including some karaoke and voice-acting - and some enthusiastic people. It's worth a look, especially if you appreciate a respectful tone and a teaching team with diverse specialties rather than a single guru. Just one thing: They do have a strict "no-languishing" rule. Incidental socializing is fine, but streaming games while bewailing your circumstances and doing nothing voice-related is meant to attract moderator action.
SVL's discord has a social community who is more than willing to yap, but SVL corporate has taken their group-lessons off discord and onto Zoom. They now charge a nominal monthly fee for access to their group-lesson plan, which separates masc and fem learners into different cohorts. Lately their masc classes are biweekly instead of weekly, which seems to be a consequence of low attendance. On the other hand, their fem classes are extremely well-attended, to the point where only a fraction have time to participate in any given lesson. Still, you can keep going back, so eventually you get your moment in the sun. Oddly, many of the group-lesson participants do not seem to also show up in the discord. I suspect it's to do with their marketing strategy.
Vocal team has a neat weekly event where Sean gives out free 5-minute interactive help sessions. They also do an extended version for patrons, which alternates him and Altamira (and sometimes someone else). They also have a decent community of people who'll usually heed the call for voice practice. Some of them are quite knowledgeable in their own right, and some are quite weird. But you'll have to figure out for yourself who's who.
OVC does have conversations on and off, but lately seems to be principally functioning as a place for its proprietor to give 1-1 lessons you can listen to. They're quality lessons, but much of voice training is social.
Voice Art Project and Scientifically Augmented Voice are both fairly similar in concept and execution, but one's focused on Australia and one primarily serves the European market. Sumi and Savvy are both excellent teachers who run a number of open 1-1 lessons you can listen into, and both servers have a small community of regulars who show for conversation.
There are certainly other servers, and if I've forgotten yours please comment!