There's something weird I noticed about Freedom Fighter on Star Rider hardware, actually. The game mostly uses sampled sound effects with some occasional typical PSG ones (like when you enter one of the three doors after taking out a tank). Does the hardware even have any dedicated sample playback hardware? I'm pretty sure Star Rider never did anything like that.
And a fun fact: The dedicated version, from what I can gather by looking at the ROMs, uses totally different sound effects compared to the prototype one.