Fediverse

The problem is not "you ordered a pizza yet are complaining it isn't a salad". The problem is you are selling pizzas and salads, but the middleman is undercutting you on the delivery of the pizzas, leaving your clients with the fake impression you sell only salads and/or provide a bad service.

All that said, from an interface design perspective the current mode is exactly how it should happen. Pixelfed and pretty much everything else are purposefully subset-specific apps. All that's needed is the reminder (as visible as possible) that content you are looking at is incomplete and you can find the more complete version on this or that URL or app. Same principle as if I wanted to eg.: design a "hashtag explorer" for the Fediverse. I'd focus on that instead of the posts (and pictures); but what I can't ethically do is prevent my users from discovering their existence.