All searches I've tried, on this forum and the wider net, find guides to removing the trim from pre-2020 models.  Does anybody know where I can find a guide for the latest please (ideally with pictures 😊)?

Found one now, though pictures have expired. Seems 2020 model is no different in this respect from earlier MkIIIs. 
 

 

there are a couple of videos here that install it on a superb mk3:

 

 

 

 

 

 

 

Thanks, I've come across those ones, but they don't cover the estate/combi hatchback, which I think has more hidden torx screws to deal with, as the lower panel is bigger.