Advice on our anxious rescue pup - trainer just made us feel worse

Hi everyone! So trying to make a longer story shorter:
We rescued a puppy (boy from Greece, 7 months old) 3 weeks ago. He's sweet, kind and lovely with us and other dogs and humans - but he's so far extremely anxious about being outside (we have to carry him outside of our door still).

It has barely gotten better in the past few weeks, even though he generally is happier when he's around other dogs (we walk several times a week with a dog friend of ours and then he manages to go to the dog park 5 min away, and loves it when he's there - but is scared on the way there).

We think it's sounds and all the new things, but inside he's more and more unbothered by loud sounds so not sure if it's mainly that or more the fear of the unknown.

We met with a dog behaviorist/trainer today as we thought it would be good to get some professional advice - and to maybe get some ease of mind that there is hope for our boy. But it just made everything worse. Or made us feel worse.

She saw him for 1 minute and then said that he was way to panicked for her to even help him and that the only way for him to get better is to get him on anxiety meds and then maybe there's hope for him but he might be like this forever. I am totally fine with exploring anxiety meds but her way of just dismissing him as a "hopeless" case after seeing him for 1 minute just made me feel awful - she also said that we shouldn't bring him outside at all for the time being. But that also means he's not going to be able to go to the dog park, which is the one thing he loves right now.

And NOTE: I have extensive dog experience , having had dogs all my life (Golden Retrievers) but this is something totally different, and now I just feel like we may have gotten a dog that will never be able to live happily in our environment . We live in a city and he will have to be able to walk on streets with lots of things happening, go on the bus/subway, visit restaurants.

Our rescue knows this fact and are convinced that he will get over it/get better, and that it's only been 3 weeks...but after our meeting today with the trainer I feel kind of hopeless.

Does anyone have any words of wisdom or advice for us?