The only thing that shows up as routine triggers for me are sensors - motion, etc. By making a virtual sensor and activating it with rule machine you can achieve what you want.
Blame Amazon. Only contact sensors, door locks and maybe some motion sensors (although for me only one that's paired with my Hue hub), are exposed as triggers. Definitely not switches or bulbs.
Virtual contact sensors work, though, and that's what I use.
The issue continues. I can get the virtual sensors (Virtual Contact; Virtual Motion with Switch; Virtual Contact with Switch) to show up as "triggers" in Alexa Routines.
Edit: The virtual contact sensor is the system device. The virtual motion with switch is the one linked to by @SmartHomePrimer, and I modified it slightly to make Virtual Contact with switch.
No sorry. I just tried setting up a new one and it's working fine in my account. These are already exposed though. I'm out, but I'll login to my system, create a new one and see if it gives me grief.
I think I read just motion and contact sensors work. Good luck, I never got Alexa routines to trigger, even when Alexa saw them. Tracking this to see if anyone has ideas
I was playing around and found that I couldn't trigger routines with virtual contact, real contact, or real motion sensors. I'm going to try cleaning house with your instructions and see what happens.