Command launch voice app

Can I run an Alexa project with an external command (IFTTT, IoT sensors, SMS, time, meteo, …) ?
I would like to start Alexa to speak when something happened.

As I know, there’s no official way to trigger Alexa without voice, except using routines.

Tiger, Not quite the same thing, but if you have Samsung Smartthings, check out Echo Speaks v3.
I use it with both Samsung and other (Smartthings) brand compatible products(Everspring, RING, Aeotec,IKEA Tradfri), including motion, open/close, temperature sensors, via Alexa to communicate low battery, low and high temperatures, loss of power through a plug and if I’ve left the freezer door open. Wyze cameras can also be configured but you’ll need an extra ‘step’ through IFTTT. You may need to create a ‘virtual’ sensor(s) that is recognised by both Smartthings and Alexa for some of the devices, but the smartthings forum is awash with info on how to do it. Link here; Hope this helps.

Thanks, I already connetted Smartthings with Alexa and work fine (when someone open the door, Alexa said: hi), but I wish to lunch a VOICEFLOW routine with a command (for example a virtual button on the screen of smartphone).