No I use it on Android for a few years already.

I am not 100% sure, but I think you don’t really need an account. I’ve had interviews where I got a link to a call/invite and opened it in the web browser. There was no need to sign in. Just enter a name and grant permissions for accessing cam and mic.

Same as in Zoom, actually.

Posting something on a public forum will never be private, no matter where exactly. There’s so much ways for this content to get “saved” like web scrapers, web archive, screenshots etc.