After a few seconds in the sun, the display goes all glitch. I wonder if there is a temperature compensation command that I'm missing.
The e-ink display works and pull request sent to esphome. Now it's time to futz with fonts and interface layout.
Unrelated FOIA find -- Public Law 86-36 redaction on an illustrated bottom. https://archive.org/details/cryptolog_35/page/n5/mode/1up
Schematics and source code for interfacing an esp32 running esphome with the Digital Smart Meter P1 port: https://trmm.net/Smartmeter/
Without the pullup, there does not appear to be any data on the smart meter's P1 port. The documentation doesn't mention that it is open-collector output and even says the output voltage is >4V for `0`. I had to buy a €15 adapter cable and disassemble it to learn this, so I hope this information helps someone else.