I'm not sure there's a device out there that meets your spec, because even though M-Bus sees wider use in European than in the US, I would expect any instrumentation performing the tasks you list to show up in the US, and I haven't seen them yet.
I still get involved with relatively expensive clamp-on (non-invasive) ultrasonic flow meters for permanent installation used for BTU billing for utility chilled water. The temperature measurements are done with 4 wire, matched pair RTDs to get the accuracy needed for the temperatures.
The kit is not cheap, not easy to carry, but it is non-invasive.
If you find something does in fact meet your requirements, please me know in reply. I'd do something to deal with M-Bus if a product like what you propose is out there.