On a microcontroller

dynamic-config-embedded is a separate no_std crate: no filesystem, no allocator, no runtime.

#![allow(unused)]
fn main() {
static SETTINGS: ConfigCell<Settings> = ConfigCell::new();

SETTINGS.store(Settings { interval_ms: 1000, verbose: false });   // compiled-in defaults
SETTINGS.apply(document, Format::Json)?;                          // from a link, or flash
}

It is not this crate with a feature switched off. A device has no files, no directories and no environment, and figment is std — so what it keeps is the shape: a snapshot in a static replaced whole, a bad document leaving the previous configuration serving, validation, and changes() for a task that would rather await. Storage is a critical-section around a plain slot, which is the one primitive every embedded HAL provides.

CI builds it for thumbv7em-none-eabihf, because "it is no_std" is a claim a host build cannot check.