[@mmc_jake]

Another option here could be to hack one of those Bluetooth Camera shutters (https://www.amazon.ca/Bluetooth-Remote-Control-CamKix-Smartphones/dp/B0113W5ZLW, ~$10 CAD). You can often find them much cheaper at Dollar Stores. If I remember correctly, these can also be mapped to a universal switch input. It may be possible to attach a mono jack in place of the switch to make a simple interface. You’ll likely still be limited to a single switch, but this bypasses the Apple authentication hurdle.