I expect a lot of people are still unaware that open source even exists. They just accept that you have to buy (or maybe rent) software from big companies. I am pragmatic about what I use. A lot of apps on my phone are proprietary.
I had a friend who was really into composing, but I have lost touch with him and have not seen updates online. He was also an open source purist who I first met at a Linux user group and I later joined his drumming circle. I expect he would enjoy your work.
Yes, Linux on the desktop and all that is more or less a lost case. I am just happy that I can use it. As for the phone I also have Android, but I am not really a phone person. I often forget it and then my wife calls me on Signal voip to get to me :)