There are other FOSS real-time voice changers for Linux, but the others I found either seemed to have fewer features, be less polished, or be abandoned.
I’m not really a voice expert or anything so I’m not sure what aspects of voice a, like, forensic voice analyst or something would look at. I’ve just changed the pitch and I sound different enough that I wouldn’t recognise the voice, which is good enough for me. Open to suggestions as to what effects would give the most privacy in terms of making it harder to identify your voice (while still being intelligible)
Also, for people’s reference, if you want mic input to be changed for all apps, go to three dots > Preferences > General > Audio > Process All Input Streams and enable.
In the meantime, its possible to use qjackctl to create a connection from input to the VST before it goes to the easyeffects sink. Its a bit kludgy but it should work well enough.