Hey how do i get peices to find the omen islands? is it all random events or can i speed it up by buying peices? help please?

The pieces can indeed be bought in user shops

what is the name of the items? i tried searching for omen island map but it doesnt show anything

they are called Uncharted Land Map Piece 1 (and 2, 3, etc. up through 9)

thank you so much!!