@scoobyx
I watched your video out of curiosity, as I do not have many issues with the BKSQ caravan sounds as they are. Big question: did you adjust the sound levels in any way to normalize them for your video, against the other two aircraft?
If not, then I don't really see a problem. This is just my personal opinion...take it however you would like, as I'm just trying to explain what I think your gripes are. I am a major audiophile when it comes to flightsim. I am quite particular about this aspect. (Back in the day I did a ton of sound modding for P3D/FSX, but the MSFS WWise system doesn't lend itself to end-user tinkering).
I think, basically, if you're inside of a single-engine turboprop such as a Caravan, PC-12, or a TBM, you would not hear the prop buzz the same as a twin like the Duke. The prop sound transmits through the airframe as vibrations leading to a continuous hum, but because it's very far forward of your ear, it's not the predominant sound as with a twin. The other engine sounds you hear inside are related to other components of the engine. This, I know from personal experience.
IMO, I don't think FTSIM has made any sound packs for MSFS that are even remotely decent, except for the MD80. FTSIM's Caravan sound pack adds a lot of bass and drama, but it doesn't sound like a Caravan. Not really a fair comparison.
You should try opening some of the ram-air vents if you want "MOAR PROP". There are vernier levers on the far left/right sides of the main panel for the pilots, as well as the dials for the eyeball vents above (behind the fuel selectors). Boris set each one of those up to introduce some variable air blowing sound and exterior engine noise. Like I said, they're variable so you really just have to crack them to make a difference (it shouldn't affect your cabin temp very much).
