I downloaded Openvibe to check it out, but didn't login, just did the test version, read-only. Some initial impressions:

It's cool to be able to see posts from Bluesky and Mastodon, which do appear to make up the majority of posts there, probably relative to the number of users.

Posts are labeled as to which platform/protocol they are from.

I didn't see any posts from Threads.

When I did see Nostr posts they were mostly Bitcoin related, unlike the others.

Unfortunately to interact with posts from Mastodon or Bluesky you have to login with one of those accounts, or create one. Personally, I'd rather not have to create other accounts on those platforms but would rather be able to use my Nostr account to interact with those others, though I realize this my not be technically possible at the moment.