Anyone fitted a dashcam on an L460? Is it a complicated fit? Is the Land Rover offering the best?

LR option is very expensive and poor imho.

Get a lead from Powerfuluk and either a Nextbase camera or a Blackview - Powerfuluk do a plug n play adapter for both and it’s a doddle to fit  "UNDERSTEER" ----is when you hit the fence with the front of the car.
"OVERSTEER" ------is when you hit the fence with the rear of the car.
"HORSEPOWER" ----is how fast you hit the fence.
"TORQUE" -----------is how far you take the fence with you.

When will manufacturers start putting a USB point by the rear view mirror. letters not necessarily in the right order

Some do have a USB socket by the mirror. Much better to use the cameras already in place as a dashcam like BMW offer as an option in my opinion. MY23 Panamera E-Hybrid
MY19 SDV8 Autobiography - Sold

I’ve gone with the JLR front and rear dashcams for the last 2 cars. It does the job but it is a bit of a faff to download.
I think of it as added insurance if the car gets damaged while driving or parked up.

Peace of mind that it’s JLRs problem if anything goes wrong with it.