Can the bed lights be wired into the 2015+ OEM bed lights so it works with button too?Updated 4 months ago

Yes they certainly can! You can locate the wires for tapping under the rear passenger door kick panel. 

For your ground wire (black) splice the black/yellow as seen below in this BCM wiring guide.

For 2015-2017 trucks please use the violet wire for power.

For 2018+ model trucks please use the white/green wire.