My favorite is an automation that triggers when I turn on my motorcycle helmet's bluetooth module, it checks the time of day and starts playing my favorite type of music for riding at that time - hard rock at daytime, EDM/synthy music at night.
It's a bit surprising to me that, say, Zapier hasn't skunkworked up something like Shortcuts that could be crossplatform. It's not immediately their core competency but being able to roll out low code UIs across employees of a phone through that would make a lot of sense.
The unfortunate thing with iOS is that while there's some secret stuff with deep linking ultimately less stuff is exposed than what one might entirely want. But I _was_ able to make a "fake" Find My for my bluetooth headphones in about 5 minutes (bluetooth disconnect -> record lat/lon into a text file on my phone) and that was fun.