I realized profound joy when I realized that an above-average number of the parents at the [non-mainstream sport] studio to which I take one of my kids were people who shared a _lot_ of my nerdy-interests. It was one of those rare "I've found my people!" moments.
And? What ARE you interested in? Books, board games, video games, anime? There are about a zillion conventions, regularly meeting local groups (basically everywhere), and other ways to interact for enthusiasts of those things.
Meetup.com often covers this as an activity, though your results may vary. Best to find someone likeminded over a niche meetup, befriend them then have drinks after that.
therapists/psychiatrists can't really "cure" depression in most cases; they can only blunt some of the worst symptoms with drugs or teach coping skills. this often plays out over the course of years. in the mean time, depressed people might want to make friendships that they can realistically maintain. this probably does not include friendships that depend on mutual participation in activities for which the person has no genuine interest.
That’s not true, not entirely. There is a variety of approaches here, but one typical approach is for psychiatrist to blunt the symptoms with drugs, just enough so that you can get yourself together and commit to seeing a psychotherapist.
Read the first two chapters from the “Feeling good” book by David Burns to get an idea of what a competent (!) therapist can do.