I didn’t know if you were aware of it. (I only learned of it relatively recently.)
JSON Feed: https://www.jsonfeed.org/
It’s like RSS and Atom, but it uses JSON which is much easier for applications to deal with than XML or RDF, plus it supports features missing from both RSS and Atom, like support for multiple enclosures with the end-user selecting their preferred format.
As far as not being dead goes, JSON Feed is very young, having been started in 2017.