How do I free the PJ-MGW1103 energy meter from the cloud and connect it to Home Assistant?

Almost, there is one more step needed - you need to check SEL pin state to see if it's set to UART or SPI. Change it if needed.

Quote:

7 SEL UART/SPI mode selection (0: UART 1: SPI), internal pull-down resistance,
connected to GND is 0 level (UART), connected directly to VDD is high level (SPI)

You also need to pay attention to SCLK_BPS:

Quote:

8 SCLK_BPS Serial Clock input for SPI. If using UART, this pin is used to config baud rate of
UART

Last night I tried your firmware and the device still showed weird readings so I proceed to a proper visual inspection of the PCB, using the microscope this time. It didn't take long until I found the culprit: resistor and capacitor on one input of the BL0942 is cracked. It's possible I somehow cracked them when I first open the device to flash it. Embarrassing, never happened to me until now...

I will try to replace these components and see if the calibration is still accurate. It's a shame I don't have 0402 smd components in my inventory

At least I am happy I found out why it was behaving like this... it drove me crazy not understanding why...

Thank you very much for your time and support and for the whole "open beken project", it's amazing!

Just to confirm, I have replaced the broken components and the device is working great now!
And for reference the resistors are 470R and capacitors are 68nF - (on the input pins 2 and 3 of the BL4092)

That's good to know, I didn't consider that. So now it also works good with OBK?

Yes, now it works good with open beken.

Added after 9 [minutes]:

Yes, now it works good with open beken.