Your two examples are different enough that I would usually choose different solutions. The first one seems to revolve around the topic of "post capitalism." If I wanted to read a bunch of recent articles on that topic I would do a google news search and then restrict the date to a given time period (1 week, 1 month, etc). Sometimes I will do a general search for the term ("post capitalism") and then add in something like "forum" or "discussion" to the search to see what comments have come-up recently. The second example has a solution which could be used for the first example in some cases as well. I'd just plug www.ecomodernism.org/ into google and see what other sites come up that link back to that page. Might be a news site or maybe a forum of some kind. These "solutions" always end up leading me "down the rabbit hole" as I find additional sites within these pages that further expand my options to explore.
Ah. I guess a really large news aggregation site then? Maybe one with lots of "subgroups" for certain topics? Shhh... Don't tell others on here I encouraged this:
https://www.reddit.com/r/postcapitalism/