So far I use: Matrix, Friendica, Lemmy, PieFed. I also follow 1 or 2 persons on Mastodon, using Friendica.
I want to try vutuv now. Maybe in the future some more services.
Now I wonder if I should really register a new account for each service. May I ask for your advice? What do you recommend?
PieFed fully covers Lemmy/Mbin and Mastodon/the microblogging parts of the Fediverse, maybe also Pixelfed/image-posting.
Friendica should be able to cover microblogging (Mastodon, Misskey etc.), the Threadiverse (Lemmy, PieFed etc.), images (Pixelfed, Vernissage etc.) as well as fully-featured long-form blogging (WordPress, WriteFreely, Ghost etc.). In fact, you can even have groups on Friendica, but I’m not sure if and how well Lemmy, Mbin and PieFed users can subscribe to them.
The only reason to have a PieFed account next to a Friendica account is if you discover that you can’t send new posts to Lemmy communities, Mbin magazines or PieFed communities from Friendica. (It happens to be somewhere between difficult and impossible from Hubzilla, by the way.)
If you want to follow PeerTube channels and comment on PeerTube videos, you definitely don’t need a PeerTube account. You can do that from just about everywhere. You only need a PeerTube account if you want to post videos yourself. You can upload videos to Friendica and embed them into posts, but you really shouldn’t because Friendica isn’t made for streaming big hi-res videos to a whole bunch of users simultaneously.
Likewise with Castopod and podcasts. Or with Owncast and video streams. Or with Funkwhale or Bandwagon and music.
Other things may be trickier. Friendica has an event calendar, but I don’t think it’s as capable of handling and editing Mobilizon calendars as Mobilizon itself.