wmbusmeters has an addon in the official repo:
It does not support auto discovery but there is a setup guide for the mqtt sensor config on the addon page.
Following this guide worked for me: https://github.com/weetmuts/wmbusmeters/blob/fe936f5062124ffa3c55c9a624717dbc43ef58da/ha-addon/DOCS.md
If you find a device, try setting it up with NOKEY:
meters:
- |-
name=WaterMeter
driver=auto
id=123456 discovered in step 6. of the addon docs
key=NOKEY
Most devices are not encrypted, at least in Germany, i can measure heaters, water meters and even the official fire alarm system without any further setup