I'd listen, and I'd bet that a lot of others would also.
There used to be a Bluegrass artist who had a show on WBCQ, a commercial shortwave station that is rumored to have pirate connections and roots. He played music from his personal Bluegrass music archive, as well as his own music. He was unusual in that he was blind. I don't know if he is still producing shows, but I always enjoyed the ones that I heard.
Radio Appalachia, a pirate that plays a lot of Bluegrass, comes on the air from time to time, to this day. They are usually logged by a lot of people.
As to how many would listen, the size of pirate radio audiences has been subject to debate for a long time. Probably the best estimate would come from the number of QSL requests that current pirates get for each broadcast, and of course they are not likely to talk about this. I have heard that 50 or so requests is a healthy number, so taking into account that people who hear broadcasts are highly unlikely to ask for a QSL, I would make a wild guess that maybe 1000 listeners might be the upper limit on those that might hear a broadcast in the USA. Overseas, it's a conundrum.