1. The domain is super important for children's programming. Logo started out doing list processing and word-based games and kids just weren't that into it; it's the turtle that really made it feel real and exciting. Scratch similarly has a really concrete and fun domain (moving sprites). The exact things that good learning environments have (lots of visuals and movement) don't seem very fun when you are blind (though maybe there's ways to experience that output that I'm not aware of).
2. My natural intuition is that voice and music are fun. Maybe there's tactile things I am unaware of. Maybe Lego Mindstorms?
3. FoxDot is a really fun programming environment for creating live music: https://github.com/Qirky/FoxDot – it's very textual, and I'm not sure how easy that is (especially if you are trying to interact while the music is playing). It's based on Supercollider: https://supercollider.github.io/ – it's possible there's other more accessible frontends for Supercollider.
4. Here's something someone did with Supercollider: https://www.researchgate.net/figure/The-technology-set-up-a-...
5. That reminds me of Makey Makey, which is very tactile and affordable. But it's basically just an input device. https://makeymakey.com/ – really you can't go wrong getting that and hooking it up to a sound player or having the kid find new and inventive ways to create tactile frontends to it. I'm sure other kids will be impressed with what this kid comes up with. Here's a page on using it with blind kids: https://www.perkins.org/resource/makey-makey-stem-activities...
6. I once created a Makey Makey project with my daughter that I was really excited about, but somehow she didn't appreciate... anyway, basically it was a simple Scratch program that did sounds and speech in response to keystrokes (what Makey Makey outputs) but the "game" was all about how the Makey Makey was wired. It was roughly inspired by this: https://makeymakey.com/blogs/how-to-instructions/lesson-six-...
7. It's OK if it's not "programming" IMHO. Building things with computers is fun and good learning. Giving the kid a new medium to build things is important, with or without complicated logic. I think there is a benefit to what I'll call more inclusively "coding" which is representing your goals and thoughts in some special format, like HTML or music notation or whatever.
8. Speech input and output in the browser is pretty easy and accessible. But I don't know of anything that brings all that together in a programming-like experience. Using GPT I bet there's something possible and not super complicated that could be created today that couldn't have happened a year ago.