Europe here. I have several friends that got diagnosed with ADHD as adults.

If you try to do it through the public system it's very difficult to even get an appointment because there's months long waiting lists. Basically if you have a job and function somewhat OK in normal life you won't be diagnosed in the public system. If you do get through it can be a long process where they want to interview your parents etc to determine if you had symptoms as a child. But you can also get a diagnosis through private practitioners and some of them function almost like diagnosis mills. A couple of video interviews and tests and you are done.