Is there a way to display only a certain folder's results in a larger list?

[Herkules97]

So when I want to find uniques, I guess I have to use
unique:name;size;date-created;date-modified !folder: online: sort:path-ascending
for the opposite to
namedupe: sizedupe: date-createddupe: datemodifieddupe: !folder: online: sort:path-ascending
?

Yes I know path isn't a part of the checks, but I usually de-dup by first selecting what I plan to delete, then sorting by one of the checked properties to manually scroll the whole list, while de-selecting what I don't think I should delete.
Also why can dupe have the setup I have, but unique doesn't work the same way? I found nothing with nameunique: sizeunique: date-createdunique: datemodifiedunique:, am I holding on to something that's being phased out? Writing the way I do is faster for me, granted that might only be because my right arrow key doesn't work.

I was going to make a thread about !dupe-from:(I've already asked about that in the past I believe) but then I thought that would be the same as unique: but now I realise it isn't. But I guess it would be unique-from: now. Is there any news on that? I don't remember what the answer was last time nor do I know where that answer would be. As in finding uniques from a specific path. Opposite of dupe-from:, hence the !dupe-from:

A possibly-worse substitute would be if you could do one of the searches above then while that list is still active, only see a certain path(so you can return to the original list without having to process for it again in case you want to see other paths). Scrolling in such a large list is slow. Mine finds 49mil files and it's hard to get any precision in a short amount of time.

It would be space-costly to export the entire thing, but it would be faster if you do have the space. Then I could start loading the export, hope it doesn't require more memory than I have and then search for the path. What I do next depends on what I find.