Membrane Keyboards can be Lighted up with the Bi colour or RGB LEDs and LGF film LGF is light guided film the advantage of LGF is you can have a uniform lighting for various icons with minimum LEDs

Advantages

Can be Selectively Illuminated
Different colours for each key possible
No MOQ
Less Inventory cost
Good Tactile feel
Can be Selectively Illuminated
Good Tactile feel
Requires very less thickness
Require less current

Limitations
Increase the thickness, to around 5.5 mm
Need more current to drive LEDS

MOQ required
Tools cost involved
Development time 3-4 weeks
Keyboard Construction

Above construction is just for reference.
KIPL resource right to make any changes to meet the specific requirements related to cost and durability.