It is absolutely safe if you do it properly.
As for the warranty dealerships say it will not void to make some money off of you, If there is any issue and details are sent to Indus, Indus will not accept warranty claim as even if it plug and play no wiring cutting etc but it is still a modification.
If you do the proper wiring with proper pins there should be no issue, Hide the wires in the existing harnesses, use heat shrink tubes and single color wire no one will be able to know that new wires were added and you can remove the stick anytime you need.