Is the Uncharted Land Map Piece for the hydrus pets n the omen islands? ping me

Yup, completing the Uncarted Land Map will give you access to the Omen and Islands where you can complete a quest to change pets Hydrus, vend at Oceans Depths, and turn in those gold trinkets.

how do u get to island once you have the pieces cuz i have them but i don't know what to do with them

In the games section, there is a Treasure Maps section. Go there, then to Omen Islands. After you submit the map it may take 15 mins or so before you gain access.

thank u so much :)

How do you get the pieces though?

The pieces usually come through random events that pop up as you play, and then some players who get them and don't want them sell them in user shops. temporarily, for this event, i believe some are available in the crystal shop.