The Seeed XIAO nrf52840 BLE Sense board has two versions in the Arduino IDE. Board version 1.0 in the Arduino IDE uses Adafruit programming tools and board version 2.6.1 uses Mbed tools ("language") ....for the same physical XIAO board. I assume there are two separate layers that these two versions represent, and either one is added on top of the board's factory bootloader? Or installing each version also installs their own bootloader first? I assume Seeed decided to switch over the Mbed in their later version because it has more relevant programming examples in the public.
Can someone explain how this all works?