I really like matcha. It is just a little go app (17MB) that is configured with a config file. You can use it to display in-terminal or, what you are meant to do, run it and it generates a markdown file as a "digest" of the feeds you configure, easy to trigger it manually or you can set up a cron job/systemd timer to do it on a schedule.
As long as I have Thunderbird already opened and using resources for reading mail, I decided I might as well use it for RSS too instead of opening another application.
Newsboat integrates RSS and Youtube (or piped.kavin.rocks which is privacy front for Youtube). It launches your Youtube videos in your video player of choice. I bet MPV is the most lightweight video player.
I've used Newsboat for 3 years and after hard hassle during the first days it has given me easily the best ad-free news and Youtube-experience.