I'm not intimately familiar with the BCM2711 but I believe it's a reasonable, albeit somewhat overpowered, processor for the application. It can be put into a variety of low power states and probably pulled out of sleep by various events like the GSM chip sending packets or accelerometer motion (frequently the peripheral chips have dedicated "wakeup" pins that you can wire to interrupts). It's not the most cost effective option by far, there are sub $5 microcontrollers with multiple cores for handling communications and real time motor control concurrently but you'd need to hire someone like me for a few months @$200/hr to write the low level drivers and design the boards. The rpi lets random web-only devs fumble their way through hardware development using whatever GitHub Python libraries they can find. If you only need a hundred scooters it makes more sense to just yolo it and buy up the remaining supply of rpis to start your grift.