Since there is no official GBA version, these are built using the Pokémon FireRed engine:
There is no official GBA version of Pokémon Diamond & Pearl. Nintendo released these titles exclusively for the Nintendo DS in 2006–2007. Any “GBA download” you see online is either a ROM hack, a demake, or a mislabeled file. This guide explains your actual best options for playing Sinnoh games on Android.
Lightweight, runs on any Android phone, uses less battery than DS emulation, and feels authentically retro. Cons: Missing some DS features (no Pokétch, no dual-screen UI), sometimes buggy, and not 100% complete compared to the originals.