Voice call implementation in Gajim is only waiting for an upstream improvement, it is already working otherwise. Sadly upstream seems slow in fixing this.
You can try this unofficial Windows version of Dino though, which supports calls: https://github.com/mxlgv/dino
Edit: and there is of course always Movim, which works fine in most browsers and supports 1:1 calls.
They probably used on of these federation “helper” scripts that just siphons up the entire fediverse. That is just a bad idea and results in a bloated database like they were complaining about.