I just found this list: https://www.hello-matrix.net/public_servers.php
I guess most of them have their instance of Riot web, so you could for instance have an account at matrix.org and use Riot at chat.privacytools.io. Just log in with your username and it will point to the correct instance.
Also, there is (or was) an instance of riot-web running in IPFS at https://riot.swedneck.xyz/
You guys need help with the Matrix instance? If you want, I can create an initial #ReverseEagle room?