1/ Launch a scene from Tasker
2/ Modify the state of a device from Tasker.
For 2), you can already do this with MQTT (Tasker handles MQTT as far as I know)
Also, in the meantime, you can use MQTT for 1). You create a « virtual » MQTT device that allows you to launch a scene (via a « device state change » trigger)
Are you designing an Android application? Just a question: doesn’t the PWA Gladys Assistant suit you?
Personally, I’ve added Gladys to my home screen and it’s like a native app, I couldn’t tell the difference.