Here is one of the most popular seeds for MCPE. There you will find 2 other Islands that are designed for survival. Resources for them are different. The first island is designed more for beginners, and the second island is the most hardcore that you can find on the Internet. To do there is simply nothing, if you want to build something. The island speaks for itself that it needs to live longer, what not under force to each player.
Suggest You use the seed on which generation the player will have to survive in harsh conditions, because You are spawning on a deserted island with a few trees. Also near will be generated for the second small island is completely empty.
Seed is for Minecraft PE 0.16.0+
Spawn of the player is on the first island:
It is a small island with several trees and flowers:
The second island will not be difficult to find, because it is visible from the first:
Survival on the second island will be more difficult, because on its territory there is not a single tree: