Termux offers to be remote controlled. For many things an additional permission is required that you have to grant MANUALLY to Automation. It will not request it.
Please consult their webpage for more info (just remember you're using Automation, not Tasker): https://github.com/termux/termux-app/wiki/RUN_COMMAND-Intent
Create a rule that will run a ping command (or anything else the checks something) every x seconds or minutes:
Create a second rule that will evaluate the result of the first rule and act upon it:
Create a rule that will use the dialer's notification and click its answer button (adapt the 1212 example number if you wish to filter specific callers):
https://server47.de/automation/images/examples/phone_call_answer
HINT: FOR THIS TO WORK RELIABLY, IT IS RECOMMENDED TO DEACTIVATE BATTERY OPTIMIZATION FOR BOTH AUTOMATION AND WIREGUARD.
Activate remote control in that app:
Create a start program action in Automation that just launches WG so it's not in the background anymore (no parameters are required for this one):
Add another action that just waits for around 500 milliseconds. Then create another start program action with these settings:
Add 1 parameters as specified, value needs to be whatever you called your tunnel:
Create a start program action:
See the chapter "Controlling from external apps" from the app's FAQ.
Create a start program action: