What is the purpose of VDD3P3_RTC pin in ESP32-PICO-D4 ?

[x_arrange]

I want to understand how to keep RTC clock working while chip logic is off(if possible)

if I connect VDD3P3_RTC to 3.3V supercapacitor/battery would it be enough? Do I need also to provide 3.3V to CHIP_PU?

[ESP_Sprite]

Unfortunately, what you want is not possible on the current ESP32 design as the RTC voltage rail powers other bits of the chip as well.

[app-z0]

Opposite question. Can I keep VDD3P3_RTC not connected?
If I dont use RealTime schematic with timer quartz 32768
Stay its float

[ESP_Sprite]

No. It powers a chip domain that is needed for normal use.