I agree with your driver assessment as someone who's used Zephyr quite a bit. If you're working with a new sensor, writing a new one is super straightforward. I don't have much experience picking sensor devices for embedded Linux, but I didn't think they had a ton of drivers for those types of devices. Bluetooth, networking, and SoCs, sure, but not so much for I2C/SPI sensors and displays and whatnot.

Tons might be stretching it. But to my knowledge there are not many alternatives for microcontrollers that have more? Hopefully one day it will be like Linux. At least they are trying to tackle the driver problem, unlike other most other RTOSes.