looking at this changed line I wonder if a less subtle prefix would be more user-friendly.

I can imagine users missing the second underscore and having a hard time to figure out why setting cfg-value doesn't have any effect - they won't get any indication of an error

I'm just dropping this in as the "McDonald's idea" of solutions. If anyone knows anything better, let's do that, but until then, this is a fallback :)

We are limited to what we can encode in an environment variable's name, unfortunately.

Sure but something like _CFG_ is less likely to be unspotted

Yeah I agree with @bjoernQ, __ is likely to be missed. I think either _CFG_ or personally I'd prefer _CONFIG_ but either is fine with me.

There's also the tedious option of renaming the esp-hal-embassy crate to esp-embassy, which would be consistent with literally every other crate (except the procmacros one).

(Unless there's a naming convention I'm missing)

(Unless there's a naming convention I'm missing)

https://github.com/esp-rs/esp-hal-community?tab=readme-ov-file#contributing-a-crate