A few years ago I built a USB FM tuner stick using the Si4703 chip from Silicon Labs, then DAB finally arrived in my area last year!! also, in the same way I've decided to make  a DAB+ FM tuner using the Si4684 chip from Skyworks and the PIC18LF25K50 chip from Microchip.
Hardware part: I use the DAB Shield board from AVIT Research integrating the Si4684 chip and its firmware, and the PIC18LF25K50 microcontroller from Microchip. I made a PCB on which you can add an SPI oled module (SSD1306, SSD1309, SH1106) and an optical output using the DIT4096 chip from Texas Instruments configured in hardware mode and master mode.
To experiment the solution you can first use a breadboard and a power supply module and use the PIC18F2550/4550 which is more popular (not compatible with the pcb).
Software part: the device is an HID, so no driver is needed, just a DLL to install.
The windows applications  are written in visual basic 2017.
I also post commented log files which can help you modify or create your own application.
What's new in 2024?
I built two real FM DAB Sticks in a Hammond USB Enclosure. The first called "FM DAB Stick LE" has a single 3.5mm jack for audio output and is inspired by a Skyworks application note where the audio cable is used as an antenna.
The second called "FM DAB Stick Analog Optical" has two 3.5mm jacks, one for connecting an antenna (Bingfu for example or a simple 80 cm long wire), the other jack for analog or optical audio output. For reasons of board space and performance, both have a real headphone output using Maxim''s MAX9722B chip and the output level is compatible with a line input. One of the particularities of this stereo headphone amplifier is that it does not require DC-Blocking capacitors, so there is no degradation of low-frequency response.
Which one to choose?:
If you have no RF reception problems and you don't need an optical output the FM DAB Stick LE is suitable in most cases, otherwise the FM DAB Stick Analog Optical is the best choice (especially for the FM band).
What do you need?:
_ Sprint Layout 6.0
_ PICKit3 programmer / MPLABX IPE (or else)
_ A firm hand for manual assembly!!!
_ Si4684 firmware: I'll let you guess how to get it FOR YOUR OWN NEEDS.
For compatibility issues between different hardware versions and to benefit from some improvements, download the latest versions of PIC firmware and windows applications.

Have fun with this project !!