@cupcakezealot @filipesm @molly0xfff
I'm not sure if this is what you have in mind, but you can follow RSS feeds in Friendica (https://friendi.ca) the same way you follow ActivityPub accounts.
If you paste an RSS feed into the search box on Friendica, it will bring it up like it was an account. If you follow it, its posts will appear in the same timeline as ActivityPub posts.