Aeotec makes both Z wave and Zigbee sensors now, but in either case, you need to have a strong backbone, so you need to have some mains powered devices that match the protocol used by the sensor, unless they’re very close to the hub. See the following community faq:
A Guide to Wireless Range & Repeaters - #11 by JDRoberts
But these days for most bathroom use cases I would use an MM wave sensor instead of a PIR motion sensor. The MM wave sensors can detect what are called “very fine” movements like a person breathing, don’t get thrown off by humidity, and can detect through clear glass shower doors. So they pretty much eliminate all of the “light turns off too early“ issues.
We use the aqara FP2 Wi-Fi MM wave sensor and really like it, but integration with SmartThings is limited right now to what you can do with Alexa routines as an intermediary. Both companies have promised there will be better integration in the future, but we aren’t there yet.
Best mmWave Sensor to Use with ST? (human presence sensor/occupancy sensor)
I know they cost more than PIR motion sensors, but the functionality is just so much better I think it’s definitely worth it. Choice is good.