The code for the first is there, its just on other branches, they seem to have a very unusual way of using git.

This first one has a QR code linking to its source: https://github.com/niilopoutanen/rss-feed

Unless I missed it, the second doesn’t claim to be open source. In any case this appears to be its source: https://github.com/maco2ou/finefeed

I’ve been using Fedora with Cinnamon almost exclusively for more than 10 years.