The bootloader will reset the device when it finishes loading the new application; This means that software resets can be initiated by both the software application and the bootloader.
The bootloadable and bootloader can both read the flash memory, so in theory you could store values in flash for access by both. Otherwise, the only similar reference is the "metadata" for the bootloader/-able which is stored in flash as well.
I was hoping that there is a possibility to share a region of non-initialised RAM between the bootloader and the application but ... ok, I will use the flash!
If anyone though, has a better idea how to recognise a 'power on' reset in an OTA bootable application, please, share it!
Yeah, I looked through the documentation for references but didn't see any that stood out for RAM or shared memory :/
Possibly there is a low-level method for doing it, but I wouldn't know
Good Luck though!