after your reply (thanxxxs!) I tested again. And this time it worked :-))) I must have messed up your original example code 'til the failure point with my supplements. This time I sticked rigoroulsy to your formulation. Success!
Regarding your literature hints: Thanks again. I had gone through relevant randomnerd tutorials before. That's how "esp_sleep_enable_touchpad_wakeup()" came to my mind... a dead end road as I learned from your remarks. The Espressif sleep docu I have yet to read.