This is such a fantastic idea, and it would be just amazing if this were to become a reality. As a fellow genderqueer individual, the thought of non-gendered bathrooms pleases me so much, especially if all the bathrooms were non-gendered. That said, I don't have that much to suggest since you've covered so many things, but here's what I've been able to come up with.

My mother has severe rheumatoid arthritis and just a few courtesies can help so much. She enjoys going outside, but she tends to get discouraged by how inaccessible so many places are, especially for someone who has difficulty walking and using her hands. Providing straws with beverages, and ensuring that everything has easy-open caps means the world to her. Even simple things, like using lightweight silverware, can be the difference between her having functioning hands at the end of the day or not.

If you ever get this project off the ground, please let me know. I'm an artist, and I would absolutely love to contribute art, graphic design, web design, or anything that I can to your project.