I noticed on the App FAQ

Anrdoid 10 + Hauwei - Throttle switch not available: Huawei has removed this developer option; no known work-around at present.

Seems I found it.

So I have two P20 pro devices. I settled on the idea I couldn't fix the missing setting for the WIFI scan throttle, till I realised one of my devices wasn't throttling, while the other was. So I used ADB to read the settings, like this: adb shell settings get global wifi_scan_throttle_enabled I ...