should I be able import this into audacity as raw audio as unsigned 8 bit PCM with a custom sample rate.
That should work. With 8-bit mono you simply have a series of bytes, and about the only thing that could go wrong is mixing-up signed & unsigned values.
Oh... The Arduino's ADC is 10-bits. Did you scale-down to 8-bits? (Divide by 4, or bit-shift left by 2?)
If there is a problem, try DC (maybe 5V and 0V) or a very-low-frequency square wave. Then, open the file with a Hex Editor
and look at the bytes.