I’ve made a handful of high F/F#/G and even a high A whistles in a few styles that might work. Should have a PVC high F finished up here in a few days for a CfA whistle set that I’m working on right now.
I found that address just now and sent an email asking about his products. I have no idea if this will work but it’s all I could find. I’d like to see about a whisolo. Looks interesting! Good luck!