I use Bluetooth in car, with portable listening, and I also I have a Sony Bluetooth brick that I use in the kitchen, back patio, and bring occasionally on vacation. I purchased an Audioengine Bluetooth receiver over 10 years ago for the mid Fi system in our living room that rarely gets used, primarily when one of my adult kids are over and wants to play music from their phone.
I use AirPlay and Chromecast to stream Apple Music, both of which are better than Bluetooth. Streaming is secondary to me vs Physical Media, but the OP said his sister would be happy with Bluetooth, as indeed most of the population is, minus those of us that post here