There is no reason why you can't save a struct (in binary-which is your configuration) on an SD card. Not much more complex than saving/restoring from EEPROM.
I usually use ESP_NOW when communicating between ESPs.
Here is a tutorial that shows how to set up ESP-NOW Web Server Sensor Dashboard (ESP-NOW + Wi-Fi).
There are a few more tutorials dealing with:-
Getting Started with ESP-NOW (ESP32 with...
Note: Another option would be to add a timeout to waiting for Serial. I often do that, as it allows me the flexibility to
have it wait some at the start for me to connect up the Serial terminal, but it also then allows me to run it without USB...
I don't see how the code above could ever have run. You declare an array of buttonPins but never use an array subscript when addressing the array items. In fact as written the program WILL NOT COMPILE!
I have corrected your code below which does...
When uploading code, can you enclose it within Code Tags using the </> button on the form.
This preserves indenting etc and makes your code much easier to read, understand and be better able to help with.
I have enclosed your code below using...
Can you supply a COMPLETE sketch that can be compiled that demonstrates your problem. Also please state what gps module you are using. Without this info no-one can compile your example and chase down your problem.
I would suggest cutting (carefully) the pins between the boards.
Attempting to de-solder and separate the boards in my mind is a recipe for disaster.
It's always difficult to pull more than one pin out from a board at the same time, trying to do...