I’m a big fan of using Shortcuts to automate against web APIs. Here are some fun ones I’ve found.
Xfinity has a TV remote at xfin.tv/access. You can pluck the tokens and requests from your web inspector, and then create shortcuts around them.
Plex lets you use the API to search your media server for content, and then push that content to an available player on your network. https://www.reddit.com/r/PleX/comments/dox9a5/creating_a_play_queue_and_sending_it_to_a_player/
Roku has a local control API that lets you send remote button presses to your box, as well as launch specific apps. https://developer.roku.com/docs/developer-program/debugging/external-control-api.md
SEPTA (Philadelphia’s transit network) has an API for their Key cards, so I can get my transit card balance by asking Siri. I can also ask for bus detours, and pull up a map of current buses on a route by plotting them on the Google Maps API. http://www3.septa.org/api/
If you use the Pihole ad blocker, you can create a shortcut to temporarily disable it. https://discourse.pi-hole.net/t/pi-hole-api/1863
What are your favorite APIs to hack against?