I set up Matrix a few days ago. I installed the telegram, whatsapp and signal bridges, so that I can have everything in one place. You can choose between different client apps for web, pc and mobile. Everything now works great behind on my VPN without any open ports - I could open a port and use matrix itself.
Yes. If you’re into selfhosting you should definitely give it a try. Under the hood it uses the Whatsapp web feature as far as I can tell. You’ll need the Whatsapp app on your phone or a spare one. But as I only use it for a few days, I can’t tell you more about outages - maybe when they change something in Whatsapp web.