From Brandon's Tinkerings
Random Notes
Updating SiLabs UZB-7 SLUSB001A USB Stick (EFR32ZG14) US.
This got me 90% there: https://github.com/zwave-js/node-zwave-js/discussions/2544#discussioncomment-1323267
However you actually need to install the Gecko v3.2 SDK
Firmware as of writing: C:\SiliconLabs\SimplicityStudio\v5\developer\sdks\gecko_sdk_suite\v3.2\protocol\z-wave\Apps\bin\gbl\ZW_SerialAPI_Controller_7.16.3_297_EFR32ZG14_REGION_US.gbl
Is then able to be written with the PC Controller.