RGB seems like a good idea but it would take up some space; 5x4 with no INSL, 4x3 with INSL, is the smallest I could get it (FILT is where your RGB would go, the VOID just shows the area):
Although I guess it's still less space than HSWC/PUMP/SWCH or LCRY pixels.
Also, the spark trapping thing is possible in a relatively small space; here is a slim array of gated D latches (roughly -- they don't output continuous sparks when on):
Pressure to vacuum will create high velocity in a direction towards the vacuum. This is because the air is being pulled and pushed in the same direction. Pressure is a force and velocity is speed.