Gawd bless ya @OldSurferDude , that just about answered every question I have to date, I especially thank you for indicating whether the item named is a software or hardware product.
On reading into the Cerbo GX capabilities I was very impressed with its sophistication and, just as you said, I will have to break the complicated parts down into bite-sized pieces and build from there.
It started with an idea for a project, essentially to take data on battery state of charge (SoC) from the Cerbo GX and use an Arduino Nano or ESP8266 to build a strategy so that I would have sufficient hot water in the morning, consistent with having enough battery power left in the evening. Only on further inspection did it occur that the Node Red software built into the Cerbo GX could do this for me...and thus the possibility that a wireless hot water temperature sensor (transducer) could be fabricated to feed that data into the Cerbo GX; hence my path to here.
I've dabbled in programming in C, mainly through the Arduino IDE, and in a previous life part of my work involved programming PLCs for industrial automation, so I am somewhat familiar with 'tech', but I lost interest once most systems seemed to go Windows based. In the intervening years the 'tech' has moved on apace and has left me behind, which is why I've struggled to follow the jargon, akin to trying to fit the second piece in a large jigsaw puzzle. Once the fundamentals are there I'll catch on.
So please, kind contributors, be tolerant of the silly questions we newbies ask, we won't always be newbies, and I'll be back for sensors stuff once I've tamed the red-hot node and sorted out my LBQTTs
Best wishes....MM