Start a tor daemon with SOCKS5 proxy:

$ tor socksport 9050

Then run yt-dlp through it:

$ yt-dlp --proxy socks5://127.0.0.1:9050 <your arguments>

How did you discover this was bypassable ?

gocryptfs or CryFS on desktop (various GUIs available) and DroidFS on Android.

Yes, just create an empty room with only you inside

Couldn't you use HMAC with shared secret key to authenticate messages while keeping plausible deniability? Since the key is only supposed to be known to the 2 parties, the recipient can deduce that a message was actually sent by the sender if he did not create it himself. I think that's what OTR was using.