Is it also possible to read a sensor directly at the Raspberry Pi MQTT Gateway? I only want to send the status of a GPIO via MQTT. Is there an example code for this combination?

Thanks for your answer!
Sorry, I forgot to mention that I want to do FOTA via an MQTT gateway. Is that working at all right now?

Hello,
can the bootloader also be used on an Atmega32U4? After programming, the Atmega is no longer recognized by the Usb port of the PC. Should programming via the IDE (Arduino, PlatformIO) still be possible or will it only work via MyController?