[onewhippedpuppy]

Typically with a factory Bose system you can either get an interface box or find another way to adapt a standard HU to work. My RX7 has the factory Bose system, I have the RCA 4V preamp outputs off of a high end Pioneer HU hooked up to the factory inputs to the Bose amps. It sounds fantastic. Basically the only trick is getting a HU to work with the factory Bose amps and you are golden. If it's a fiber optic interface it is possible but gets pricey, at that point it's easier to just pull new wire from the HU to the factory speakers or tap into the factory speaker wiring to bypass the Bose amps.

Based on what you said about your daughter, find something with Apple Carplay. It is a great interface for an iPhone user, basically emulates your phone on your HU.