Connecting Nextion NX3224K028 HMI display to KC868-A16S?

[markusd1984]

Is it officially supported to connect a Nextion HMI display (NX3224K028) via UART to the KC868-A16S?

If yes, I need clarification on how to wire it safely:

1. Which pins for TX/RX? I know I cannot use the I2C header (GPIO 4/5) because it runs the PCF8574 relay chips.
   
2. The Boot Issue: If I use the GSM header (GPIO 13/15), how do I prevent the ESP32 from failing to boot? (Since GPIO 15 is a strapping pin and Nextion holds it HIGH).
   
3. Power & Pinout: Where is the safest place to pull 5V/GND, and what is the exact physical pin order on the board so I wire my custom cable correctly?
   

I want to use it as a backup to control the relays in case HA / network is offline (to manage my heating thermal actuators).

Thanks in advance!

[admin]

if you don't use 4G module, you can use GSM RXD,TXD for Nextion display.
GSM:
RXD:GPIO15
TXD:GPIO13

5V also can get from 4G module socket, there is "V" is 5v. T is "TXD". R is "RXD"