The manufacturer documentation which is mentioned a few times in this thread indicates that maybe you could do more with the device, see 3.3.4.1.3 InterFaceMode, but I think there is a catch.
I noticed that the Frient I bought came with a read head called “LED”. The documentation mentions other supported head types. I would imagine that this head can only read light pulses. My assumption is that there is nothing stopping the end-user from replacing the head with an IR read head and setting the interface mode to IEC62056-21.
Reading the OBIS data packets from my ISKRA MT681-D4A51-kp (Schltg. 4000) would also be an ideal scenario for me but I haven’t tested simply changing the interface mode yet to see if the LED head can handle the task. I’m still fighting to get it working correctly with pulses. Changing the pulse_configuration to 10,000 alone has been quite the adventure so far as I refused to abandon my existing ZHA integration for a single device but I think I’ve got it. I’ll try and document any knowledge holes in this thread as I see them later on.