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.