I will of course try to support any effort made to make an HA integration out of the NBEprotocol, but myself I don't really understand the point... Maybe someone could change my mind... :-)
Have you tried starting the Android app lately?
It takes on average 30 seconds from starting the app, showing splash screen, waiting for it to connect and read all needed values. This is perhaps what annoys me the most about the app. And then you even have to wait every time you open a new screen. The usage graph screen takes on average 35 seconds to load, and then it even keeps reloading data every so often when you are looking at and browsing the graphs.
If it would just start and then load the values in the background, perhaps blanking out the values until loaded.. but nooo, you have to wait, every freaking time...
Obviously if you don't use HA, but PellMon, then this doesn't really make much sense, but for me, that already have a HA setup, then setting up PelMon would not make much sense, as it basically implements most of the same features (from what I can see) - at least the ones I would be interested in.
Besides that I have actually really wanted the ability to compare my usage graphs with weather information. Looking at historical usage makes for very poor comparison. For example: This and last winter has been quite mild, compared to 2017.
Some sort of normalization with outside temperature and/or wind would really make those values more useful when you try to see if any changes to the house has actually saved any amount of fuel burned.
I guess such would be quite easy to implement in PellMon, if not already done, and also in HA, but the Android App... yeah, I generally try only to use it when I absolutely have to, when making any config changes.