I solved a problem posting images using wordland.social. To do so, I used a kind of "random walk" to get there, so I didn't remember which of several things I did that made it work. I subsequently went back and found how to do it "officially".
To enable the JSON API within Jetpack:
- Go to Jetpack > Settings
- Scroll to the bottom to find the Modules link in the footer
- Scroll through the list to find the JSON API
- Activate it
This is described here: https://jetpack.com/support/control-jetpack-features-on-one-page/
