you can follow pixelfed accounts from other fediverse issues with mostly not problems, you can comment and see comments from any service in the fediverse. That is: fediverse integration works as intended.
But Pixelfed is a social picture sharing application. You can follow a mastodon account, but pixelfed will only show you the media posts from the user, not the text ones (unless they're comments on a picture) for instance. As some other features mastodon posts have that pixelfed ones don't will not also work.
Conversely, you can follow a pixelfed account from mastodon, but most mastodon implementations don't support picture albums of over 4 pictures, you will not see over 4 pictures on the post.
That is working as intended though, they're different apps with different features, just talking the same language.
gotta get some liquidity to keep the base happy for the midterms.