It's not a perfect system, but I use GitHubs RSS Feeds to watch Rancher Releases (I do the same for RKE2 as well)
https://github.com/rancher/rancher/releases.atom
GitHub issues I find to be too noisy, so I haven't put work into figuring those out, they don't seem to have an RSS feed from GitHub.
I've piped mine through PowerAutomate to filter out any "-rc" releases