I stumbled across a public Monero room for Session messenger. Add this link in the proper field under "Join Open Group":
http://202.61.245.158/xmr?public_key=f3ea00d5a2f8ec3fbc6db632a66a7e489aeb37f18690e320f180ca3de9b25e42
I have no idea who runs this room, and I have no idea what their moderation policies are. At the time of writing, there are 74 members there.