I use FeedMe with FreshRSS myself, but also gave Fluent Reader a try recently. I still prefer FeedMe over Fluent Reader for the way it presents the feeds, but otherwise it is an alternative open source app that functions reliably.
It has a desktop version too.
Because not everyone agrees with each other on project directions or goals. In this case the developer is trying to learn something about flutter and dart while honing his coding skills. It's actually all explained in his git repo.