You can use a Raspberry Pi Zero W / Zero 2 W together with the [link|https://poolsidefactory.com/collections/frontpage/products/airplay-audio-streaming-adapter-for-apple-30pin-dock-connector|Poolside Factory Dock Adapter|new_window=true] to stream music wirelessly to the 30pin connector via AirPlay 2 or SpotifyConnect. The adapter powers the Raspberry Pi and contains a HiFi DAC that takes the digital audio signal and creates a HiFi audio signal going into the 30pin dock connector. It also creates the signals for your dock to think an iPod is connected. These are the [link|https://poolsidefactory.com/blogs/how-tos/turn-your-raspberry-pi-into-an-airplay-streaming-adapter-for-the-apple-ipod-hifi|instructions|new_window=true] for how to configure the Raspberry Pi for Airplay 2.