I took the liberty of downloading and flipping kaihp's photo for test purposes.
First thing I learned, do not drag and drop a file into the text posting box, just don't.
Clickable to the same thumb.
Clickable to the medium, resized by the forum.
Clickable to the large.
Clickable to the Gallery post
clickable to CR forum home.
OK, once an image is posted, Gallery creates a thumbnail that shows in the, in this case, 'Camera Body' Gallery.
Gallery also downsizes to medium while saving the original.
I didn't try other sizes, I used only this one, known to be acceptable to the Gallery software.
I don't see anywhere in Gallery's interface where it enables link creation.
The create the linked thumbnails, I first gathered all the URLs, then pasted the thumbnail's URL between the BB code IMG tag like so without the #s
That line was then highlighted, the link URL added with this post's 'Insert Hyperlink' icon in the editor.
I can't imagine doing this on a phone. Well. I can, but I'd rather not.