@pfefferle I also added the php snippet to the post template as per the final step. But no block appears on the front end. I put a little test <p>position for fediverse block</p> alongside the php snippet and that appears on the front end, so the location is correct.
So, no idea what I'm doing wrong, I've double checked every step. The site I'm trying to set it up on is https://monstertoyblog.com