The main task (the one that calls setup and loop) is pinned to core 0 in Arduino. Your loop is while(1); so this will occupy quite a lot of core 0's time. Delete or suspend the task instead. There are FreeRTOS utilities to help debug issues like this: https://www.freertos.org/a00021.html#vTaskGetRun...

No, it can't multiply or divide. You can left and right shift though, so if the required logic can work with powers of 2 then you can multiply and divide using shifts. Other options would be to write subroutines for these operations if you really need them, or gather raw data and let the SoC process...

- Writing to ULP program memory while it's running can cause all kinds of issues. Make sure it's not still running before reinitialisation. Note that it's in the RTC domain which survives most resets, so even a esp_restart() after an OTA update could leave the old ULP program from the previous firmw...

Yes, it has the pulldown enabled. It's not undocumented though, see table "A.4. IO_MUX" in the datasheet for all pin configurations at/after reset.

1000 bytes is a very low stack size. Try 4096.

Side note: The comment on priority is wrong (0 is lowest)

You're missing a bunch of the #includes from my above comment.
And you will need to add component dependencies to your 'my_boot_hooks' component's CMakeLists.txt:

Could you please share the code or instructions on how to do this? I'm not proficient in tinkering with the bootloader It will probably be easiest to use the bootloader hooks feature. Take a look at examples/custom_bootloader/bootloader_hooks. Bootloader RTC reset example: #include "soc/rtc.h" #inc...

Incidentally, there is a Kconfig option to reserve memory at the start of RTC slow memory - it's designed for the ULP, but there's no reason why you can't use it for anything else. If your target supports it, you can enable the ULP and then the option to set the size of this reserved area will appea...

It's unclear from the schematic but your slide switch almost certainly has 3 pins, allowing you to define the level for both positions. Connect one to GND for "Off", and the other to 3V3 through a 10k resistor for "On". You can do away with R7 then, and arguably the reset button too.