If it was me i'd still have it as a separate circuit but technically you could do what you say.
The problem being if you turn off the other lights you wouldnt then be able to use the highlight lights
Yes I get that, just thinking in those situations I would rarely have all of the other lights off, I'd just have them on a low brightness, with the art spot on full.
So right now my initial electrical works are looking like this:
Bedroom 1
Spotlights in ceiling on one circuit (Shelly dimmer2 x 1)
Pendant bedside lights on their own circuits (Shelly dimmer2 x 2)
Light switches either side of bed (3 x gang - what varilight plate would I need, brushed steel finish?) with 3 G102SRS in each
Light switch by bedroom door (1 x gang, with 1 x G102SRS in it)
Bedroom 2/3/4
Spotlights in ceiling on one circuit (Shelly dimmer2 x 1)
Light switch by bedroom door (1 x gang, with 1 x G102SRS in it)
Landing
Spotlights in ceiling on one circuit (Shelly dimmer2 x 1)
Light switch by bedroom door (1 x gang, with 1 x G102SRS in it)
Shelly motion sensor (for kids coming out of their rooms at night)
Have I got that right? Just not sure what switch plates to go for..