Both Mastodon and Lemmy provide RSS feeds. Plug them into any RSS reader, and you are done.

https://lifehacker.com/tech/bluesky-and-mastodon-rss-feed

https://join-lemmy.org/docs/contributors/04-api.html#rssatom-feeds

https://www.theverge.com/2024/12/18/24323903/flipboard-surf-fediverse-social-web-app

I haven’t tried it out yet, but maybe this

You have Mastodon and Lemmy covered with a piefed, friendica or mbin instance.

You can follow RSS feeds from a (microblogging) fediverse account using https://rss-parrot.net/ - so that covers that part. Apparently Bluesky provides RSS feeds, so this also works for Bluesky, although I have not tried that yet because I’m not aware of anyone posting only on Bluesky that I would want to follow.

Mastodon, Lemmy, and Bluesky all provide RSS feeds for some of their pages, so you can sort of do this with just an RSS aggregator. It wouldn’t do everything you asked for but it would be a start. I follow some Mastodon users and some Bluesky users’ RSS feeds, unsure if you could also get a RSS feed of a Bluesky feed.

I use Miniflux: https://miniflux.app/. It’s web based so you can access it on any device. It’s open source so you could run your own instance, but they also have a paid version which is just $15/year. It works great and the price is super cheap so that’s what I use.

Am I wrong or does pyfedi do something like that

As a workaround there are Lemmy servers (don’t know which one off the top of my head) that basically mirror RSS feeds to their communities. And with Mastodon you should be able to follow them.