Getting pin status hardware side after app button

Hello all,
New here obviously.
I am using Blynk in its basic form to turn on and off the built in led of the standalone esp8266 d1 mini.
My question is, how can I detect the status of the d4(BUILTIN_LED) pin on the hardware side after pushing a button on my app.
I need to start PID, timer, and temperature logging, when this Blynk button is pushed. Ive read through the DOCs section and turned up nothing.
Thanks for any help

Detecting a digital pin status is really an Arduino question, not specifically Blynk related - use digitalRead() for that (might not work as well on the built in LED due to internal resistors??)

But the proper way to do what you want is using >virtual pins<. Set the button to V0 and then use something like

BLYNK_WRITE(V0)  // This function is called when pressing an App button set to V0
// Do stuff here

Many examples can be found >here< Look for “Widgets/PushNotification/PushNotification_Button”