Yes, I have to be that pedantic person - this is absolutely false. In fact, here in NC is one of the primary centers which trains seeing eye minis & their waiting list is very long. The mini horses are very successful guides for the blind.
To Op, I teach all my horses to ride roads safely, there’s a huge & useful skillset to be had. I ride and sometimes pony a 2nd horse to lessons (2 for 1 exercise). I make the horses carry my crap tho, I have a saddle bag with water bottle holders & zippered pockets. Saddle bag can easily be removed for lesson if needed. My phone is always velcroed to my calf tho - don’t attach it to the horse just in case you get separated.
Do make sure you are very visible. Do NOT ride with headphones in, you need to be able to hear. I ride on whichever side of the road has room for me (bc it’s rarely both) & always lookout for roadside debris.
And always tell someone when you are coming & going so if you don’t arrive, they know where to look.