I have a ton of experience with batteries and battery architecture. And i can assure you without hesitation that while Bosch may have their own plugs that include a key sensor, they still connect the battery with the same red and black wire everyone else in the entire industry uses.
Bosch ebike batteries at a minimum have 3 conductors, Pos, Neg & the CAN bus line. Bosch ebike batteries have their own Firmware & record s/no., min, max temp, charge cycles, voltage, etc. and can supply the motor/display this information via the CAN bus, also can be switched on & off via the bus.
With conventional ebike experience you would think you could measure the battery voltage at the + & - conductors too but no, not with the Bosch ebike battery.
Their default state on those conductors is open circuit.
And with your experience, get your horns around
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the following picture of an older Bosch ebike BMS, i think you would have to agree that it's a bit more complex than the average bear.
This complexity allows for the following on a dual battery system:
Charging: bat1 charges to approx 80%, then bat2 to approx 80% then both batteries are simultaneously topped off (CV) to 100%.
Usage whilst powering the motor: bat1 is used for approx 5% of it's SOC/DOD, then bat2 for approx 5% of it's SOC/DOD, and repeat.
This keeps the batteries at a similar SOC/DOD and also allows for chemistry/temperatures to settle/cool.
Also safety as to when the bike is off there is no major power on the cable harnesses.