Signal Messenger, LLC 650 Castro Street, Suite 120-223 Mountain View, CA 94041
https://signal.org/legal/ Signal Messenger, LLC 650 Castro Street, Suite 120-223 Mountain View, CA 94041
https://lmy.de/page/impressum If you have your own domain, then yourls could be a solution and install it on the server itself, as I once did here https://b-ge.de/y/. Buy from EU https://b-ge.de/y/eu
Edit: A few advantages of hosting your own URL shortener on your own web server like yourls. I have captcha configured, but that's just protection because my server is very weak and I can do without it. Unpacked in the subdirectory, this also works for all other domains as a symbolic link, e.g. https://babsi.de/y/eu or https://babsi.de/y/bfe is also b-ge.de/y
I don't think Signal is a video conferencing solution. It can do video telephony, but I don't know Signal as a video group conference.