I see “your age” similar to the dating pool. It grows the older you get. When I was young my brother and his friends were incredibly old. But nowadays they are “my age”. I mean, my wife was literally born four days after my brother. That alone increased “my age”.
And when I look at the other parents I meet at my kid’s schools “my age” is an even bigger group. Add hobbies to that and it’s off the chart.
The only problem that I see with this is that images and especially videos take up vastly more space than plain text.
And does ActivityPub include client APIs? I haven’t looked at it, but my completely unfounded impression has been that it only handled server to server communication.