I do something similar at home. However, the meter in my house has a LED that blinks per Wh used, so all I did is put something light sensitive on top of it, wire it to a tiny board of your choice (GPIO on a Raspberry Pi in this case) and then export the data from there. I run a tiny Prometheus exporter on that same Pi which gets scraped and everything neatly shows up in Grafana.
For other devices I use Z-wave powered sockets which do power metering, which is exposed by another Prometheus exporter. Since those Z-Wave sockets can be on the expensive side I only really use them in places I want to meassure, like my desk (which has laptop, screen etc.) or the TV.
This gets challenging when you have solar export and a bidirectional meter. The light blinks for every _absolute_ kWh. That is, you don’t know if that was imported or exported electricity, so you need additional information. One approach I’ve seen is to use current clamps just to work out the difference between what’s coming out of the solar inverter, and what’s going into the house. If a > b then the blinks are export, and vice versa.
For other devices I use Z-wave powered sockets which do power metering, which is exposed by another Prometheus exporter. Since those Z-Wave sockets can be on the expensive side I only really use them in places I want to meassure, like my desk (which has laptop, screen etc.) or the TV.