hahahaha, ich lach mich tot.....

JA!!!

sogar ohne static und ohne thread_local:

Code:
#include <Arduino.h>
#include <thread>
#include <chrono>

#ifndef LED_BUILTIN
#define LED_BUILTIN 13
#endif

const auto one_sec = std::chrono::seconds
{
    1
};

void counter_loop() {
    uint32_t counter = 0;
    while(true) {
        Serial.print("counter_loop: ");
        Serial.println(counter);
        std::this_thread::sleep_for(one_sec);
        counter++;
    }
}

void blinker_loop() {
    uint32_t counter = 0;
    while(true) {
        digitalWrite(LED_BUILTIN, HIGH);
        Serial.print("blinker_loop (HIGH) counter: ");
        Serial.println(counter);
        std::this_thread::sleep_for(one_sec);
        
        digitalWrite(LED_BUILTIN, LOW);
        Serial.print("blinker_loop (LOW) counter: ");
        Serial.println(counter);
        std::this_thread::sleep_for(one_sec);
        counter++;
    }
}

std::thread counter_loop_thread(counter_loop);
std::thread blinker_loop_thread(blinker_loop);
    
void setup() {
    Serial.begin(115200);
    pinMode(LED_BUILTIN, OUTPUT);
    
}

uint32_t main_loop_counter = 0;
void loop() {
    main_loop_counter++;
    Serial.print("main loop: ");
    Serial.println(main_loop_counter);
    delay(10000);
}
main loop: 1
counter_loop: 1
blinker_loop (LOW) counter: 0
blinker_loop (HIGH) counter: 1
counter_loop: 2
counter_loop: 3
blinker_loop (LOW) counter: 1
blinker_loop (HIGH) counter: 2
counter_loop: 4
counter_loop: 5
blinker_loop (LOW) counter: 2
blinker_loop (HIGH) counter: 3
counter_loop: 6
counter_loop: 7
blinker_loop (LOW) counter: 3
blinker_loop (HIGH) counter: 4
counter_loop: 8
counter_loop: 9
blinker_loop (LOW) counter: 4
blinker_loop (HIGH) counter: 5
counter_loop: 10
main loop: 2
counter_loop: 11
blinker_loop (LOW) counter: 5
blinker_loop (HIGH) counter: 6
counter_loop: 12
counter_loop: 13
blinker_loop (LOW) counter: 6
blinker_loop (HIGH) counter: 7
counter_loop: 14
counter_loop: 15
blinker_loop (LOW) counter: 7
blinker_loop (HIGH) counter: 8
counter_loop: 16
counter_loop: 17
blinker_loop (LOW) counter: 8
blinker_loop (HIGH) counter: 9
counter_loop: 18
counter_loop: 19
blinker_loop (LOW) counter: 9
blinker_loop (HIGH) counter: 10
counter_loop: 20
main loop: 3
counter_loop: 21
vielen Dank an euch beide, das ist jetzt echt ne super Basis um weiterzumachen!
Ein Riesen-Schritt für die Menschheit!
großartig, danke!