If you are into video conferencing and screen/window sharing but don't want to use WhatsApp, Signal, Telegram, Teams, Google Meet for security reasons (or others), try Cyons's Meeting Service. It is based on Jitsi Meet (open source) and operated, for example by Cyon, my Swiss-based hosting provider, or Switch, the former Swiss "internet provider". Jitsi Meet runs native in all major browsers - except for Safaris probably and Google Chrome probably to be the bast alternative from a compatibility point of view. For iPhone and Android, respective applications are available for download.
if you want to have a bit more privacy and control over your video conferences, try moderated Jitsi meetings.