My birds go outside virtually every nice day. Three of my five are "out and about" trained. I take them all over the place. Especially my greenwing.
None of them are harnessed. They are clipped, semi-flighted, and recalled.
My birds are also "stay put" trained.
It tends to blow people's minds, but I can set my birds down on the back of a chair, or in a tree outside, go in to Starbucks and get my coffee, and come out to find them exactly where I put them....
My red lored has been to the Carnaval parade in SF... 250,000 people, drums, floats, dancers, loud music, and one very happy out and about birdie...
Both my macaws pretty much go everywhere as well...
We go for walks all the time as well. Used to go out nightly.
My Greenwing's favorite thing is laundry day. I bring her big playstand and set it up out in front of the laundry mat, and she sits outside while i do the laundry. I am outside playing with her unless I am folding, or loading, or changing over loads... (Cuz let's face it, laundry is boring!) It's part of her outside time, and part of our 1 on 1 time....
My red lored amazon also has "special tree privileges." Unlike where we were in California, there aren't as many predators around here. So, I frequently just let her go outside and sit in the tree in my front yard, sometimes for as much as 7-9 hours at a time. (She comes down to me when I call her. Every single time, for over 10 years... so I consider her 110% trustworthy.)
The two I don't trust are my CAG who can (and has) spook and fly off on me... and my shy little lilac crowned amazon, for the same reason. NEITHER of those birds like going out and about anyway, (while my other three beg to come every time.) So, those two go out in a tree in my front yard, when I am out there with them to keep an eye on them... otherwise, they are indoor birds.