Yeah, the 5 environment configurations is not the same as 5 programs. As you can see in the screenshot below, it refers to the classification of Very Simple to Very Complex configurations in order to figure out how to divide and set the Neural Noise Suppression max values for Easy and Difficult classifications.
Having said that, I would not worry too much about having only 1 general program on the Own. Oticon aids are designed to work sufficiently well with just a single General program for the most part, so you just give up on having the flexibility of customized setups, that’s all. The General program should work fine for music and also speech in noise as well, so no worries.
As far as your singing goes, even if you had multiple programs option, I don’t think it matters as much on how YOU sound to yourself between different programs anyway. So you don’t need multiple programs to be able to hear yourself sing better in one program vs another.