I recently installed a Nextbase 622GW front and rear camera system in my Toyota C-HR Design (2021 petrol hybrid model, right hand drive, UK model) powered via permanently live fuse. I wasn't able to find a fully detailed guide online so had to work some of it out myself, so I'm writing this guide to help anyone else who wants to fit this.
I assume you have the front and rear dash cameras and a hard-wiring kit from Nextbase.
The reason to have the Dashcam permanently live is to take adv