I want a to-do list app that syncs from a json file (or other human-readable data format), so that I can view and modify the file (via a CLI like jq) from my computer too, and it would still reflect on my phone when it syncs.
Does this exist? Preferably it uses a format simple enough that makes it possible / easy to modify it via jq.
You can literally export all your notes in 2 clicks. You right-click on your notebook, hover over the export menu and select Markdown. Choose a location and Joplin will create a folder with all your notes in Markdown format inside.