HN user
For what it's worth, the cell metadata in the post is from over a year before I even opted-into the SMS integration.
The SMS integration was disabled after a few weeks of usage, the app was too buggy.
Checking now, it looks like both of them have WhatsApp accounts.
My particular case was not related to WhatsApp (OP of the tweet here) as I had never installed or used WhatsApp until yesterday.
AVR-Rust author here
The backend itself is working very well - there are only a handful of known bugs at this point, and many projects can be compiled with no issues.
The issue you linked also links to (https://github.com/rust-lang/rust/issues/44052), which shows that once these bugs are fixed, we can start working on merging avr-rust upstream.
A number of projects/libraries have also been developed recently
* https://github.com/avr-rust/blink * https://github.com/avr-rust/avrd * https://github.com/avr-rust/arduino * https://github.com/gergoerdi/rust-avr-chip8-avr