List of exported metrics gets reset  

RE: List of exported metrics gets reset

Ok, judging by https://github.com/prusa3d/Prusa-Firmware-Buddy/blob/HEAD/src/marlin_stubs/M330.cpp#L30-L46 , it's working as implemented: metrics are toggled on/off only in RAM, not persisted anywhere, and upon boot the state is what's statically compiled into the firmware binary.

void PrusaGcodeSuite::M331() {
    if (!config_store().enable_metrics.get()) {
        SERIAL_ERROR_MSG("Warning: Metrics are not enabled");
    }

    for (auto metric = metric_get_iterator_begin(), e = metric_get_iterator_end(); metric != e; metric++) {
        if (strcmp(metric->name, parser.string_arg) == 0) {
            metric->enabled = true;
            SERIAL_ECHO_START();
            SERIAL_ECHOLNPAIR_F("Metric enabled: ", parser.string_arg);
            return;
        }
    }

    SERIAL_ERROR_START();
    SERIAL_ECHOLNPAIR("Metric not found: ", parser.string_arg);
}

I guess short of building and flashing my own firmware my best option is to add a bunch of M331 commands to the start G-code, which would be, uh, suboptimal.