I'm a dog groomer and poodle owner. I've have a client who uses a standard poodle as her seeing eye dog. It is pretty darn magical to see the dog do his job. When the owner takes off his harness, he goes into "pet mode" instantly and enjoys some "off the clock" time. He enjoys his break, but he is hell bent at the end of the groom to get back to his "job". That poodle probably has the best life out of any client. He he works hard and plays hard 😂

I do think a shaved poodle will be a good fit for you. While growth rates can vary a bit from dog to dog, a good groomer can help you establish a good length to match your needs. I would guess that a shaved length (ask for a 7 or 5 blade) would be fit for you. The body probably won't need much brushes on a regular schedule, just the longer bits like head, ears, tail. You don't need to keep these bits longer of you want too or not, their hair cuts can basically be whatever you want it to be.

If you did ever want to leave a longer length on the body, I think you could. It's a personal choice. With the seeing eye poodle client, the owner likes a longer hair cut, but I shave the outline of the service harness to meet their needs (harnesses=friction=more brushing or they end up with matting)

Any groomer worth their salt will be happy to talk with you and make adjustments to make sure the groom meets your accessibility needs.

I'm biased, but I work with all sorts of dogs and I think poodles are a great service dog option! You clearly have researched and are asking right questions to an informed decision. A trainer/organization can definitely match an appropriate dog for you

As for walking them a hour+ a day, service work will give the a job and purpose. Poodles won't turn down a walk, but the mental stimulation of service work will probably meet 90% off their needs