I've just got my #lilygo T-SIMCAM to wake up on receipt of a TXT. Involved some hacky wiring but it does work. The issue is the T-SIMCAM doesn't expose the GPIOs I need, but I could steal one from the microphone cos I don't use the mic.
Posted details in my blog
https://madurasoftware.com/blog/waking-a-t-simcam