Personally I'm not that confortable on places like Discord and Slack since I can't keep up with the wave of messages. My replacements have been Facebook Groups, in the early days of FB they used to be so good but they fall out of fashion until recently (on my social sphere at least); some good specialty communities have emerged and they're awesome.
I've the same issue with some local news webpages and government sites, but I've been using PolitePol[1] to generate the feeds; they're not great but get the job done. Right now I'm looking for projects like RSSHub[2] or RSS Bridge[3] to have a similar service but self-hosted and without the restrictions of the free tier of PolitePol.
I think in the future RSS will be a community driven effort, not something that the website themselves care to implement.
The only reason why I keep a FB account tbh.