The following questions need answering...
I don't know what format the captured data is.
I suspect that it's an 8-bit ADC sample of the DAB station at 8MHz. Is this right?
Are the sampling parameters configurable to improve processing?
We need more information about the 0x91 VENDOR command.
What values are used to tune to particular frequencies?
Is there a simple table in the specification that could be released to the developers?
Not really anything to do with the Linux development, but is the aerial intended to be detachable? Is it possible to detach it (without voiding the warranty).