In the end it was quite easy to set up the PZEMs, the first “difficulty” was to descide which ESP-board to use, and from there how to wire it, the second is that the PZEMs have an internal addressing that needs to be updated for two of them if they are to be connected to one sinlge ESP-board, how to is described over on the esphome.io webpage
I settled for a DIN-rail setup:
ArduiBox ESP - ESP32 Prototyping DIN Rail Case (inc. ESP32 Board)
There are cheaper solutions, but this one was convinient for me.
My setup has been working flawlessly for nibe nonths now, monitoring the boiler (geothermal heat pump).