Maybe contact this specialized organisation, as they will help to find the right dog (breed) for your needs:
https://usserviceanimals.org/blog/psychiatric-service-dogs/
And while he is still young, you could start him getting used to get his teeth cleaned. This will save him later vet visits and anaesthesia for dental cleaning.
There are a lot of different kinds depending on the purpose, but something like this
or this works nicely.
Nowadays they even sell Dremels especially made for dogs:
He might have gotten hurt while having his nails clipped, which often leads to dogs that will not allow anyone to take hold of their paws for fear of experiencing this pain once again.
I think it more important to restore the confidence, than clipping his nails every week.
Just play with him...
Our dogs don't get commercial dog food (kibble or canned) at all, just raw venison and chicken, cooked wild boar with rice and vegetables, boiled eggs and potatoes, curd cheese, natural yoghurt, grated raw vegetables like carrots etc. and brewers yeast, pestled egg shells, linseed oil etc.
Yes, I do have a smooth coated Foxterrier and an Airedale Terrier.
Both are strong willed, which is a special terrier trait. But they also are very smart and therefore easy to train. They love to interact with their owner and are eager to learn new things.
Although they love to please, they are...
Her daily maintenance (groomers say you should count in at least one our of intensive brushing etc. per day) will keep you busy, that's for sure. :D
Read the link I posted and watch some videos on the topic.
Rather ask professional dog groomers, they know best as they are confronted with the results of such statements.
https://www.backyardchickens.com/threads/help-im-looking-for-a-dog-breed-that.1449453/post-24120988
This does not go well together as this little girl will need even more intensive grooming than Airedales or other wire-haired dog breeds. And more often also, otherwise they will get matted.