See also Zello. It doesn't have the e2e stuff afaik, but works on all major platforms, including mobile. They also have a native desktop app (not Electron). As

See also Zello. It doesn't have the e2e stuff afaik, but works on all major platforms, including mobile. They also have a native desktop app (not Electron). As far as I know, it's used a lot, mostly by drivers for Uber or similar services. I haven't used it for a couple of years now, but it's worth giving it a go.