if you mean taking a parrot to visit people and act like a therapy dog to cheer them up. Most parrots don't want to be touched or held by strangers. Parrots also have a phobia about new stuff. There are always individuals in tge parrot world who might do well. If it was to just bring parrot and have other look but nit touch that might work better. People are fascinated with beautiful parrots.
Interesting idea
Oh- I FULLY believe in parrots as visiting therapy animals (ONLY if they are comfortable with it)--In my post, I was talking about the people who have registered therapy animals for their own mental health conditions. Traditionally, therapy animals love their "owner" and accept new people--- parrots are not always that way....They are LOUD, messy, destructive and require extreme sensitivity to change and environmental products.
Now, when it comes to bringing a parrot to a hospital or school etc (so long as the air isn't filled with bleach or teflon

) then that CAN work really well, with the right parrot/owner (but there are great owners with great birds that would HATE that experience...soo...it's inconsistent-- never assume your bird will like you, or anyone lol).
I have had SO many students meet Noodles--- but small doses are honestly probably better-- you don't have to see/feel the insanity that some birds can be lol. When I am around, I am like Noodles' translator to others-- I say, "oh, she really likes you" (and then take their hand in mine (cupping mine over theirs) so that if she does bite, she bites me...Sometimes I say "Oh, she just gets nervous but you can talk to her!" (AKA --you will be bitten if you try . Even with kids she loves, It is ALWAYS hand-over-hand (and so they get all of the benefit of her jokes and cuteness without any of the crazy hassle/stress load/ hospital bills lol).
They FASCINATE kids and adults and if they are with "their" person, they often put on a show and act nicer than they would if some other person came around them alone..The "show" is such a small part of living with them 24/7, and to get your parrot social (and Noodles is very social), they have to be cool with you first AND have an outgoing personality on top of that...So, in the event that you have a parrot who is interested in other people, a strong trust in a bird's person will make the bird feel a bit safer around unfamiliar people. I think that as visiting therapy animals (as long as the environment is safe for them to breathe), some parrots can be PHENOMENAL for visiting therapy-- but, living with them is a whole other ballgame. If someone is struggling to meet his/her own needs or missing work due to mental illness, I would avoid parrots-----They need too much, too often, too long and they are expensive as heck.