ES1 is implemented entirely in the front-end using features from GLES3.0. Therefore, every backend with GLES3 support (i.e. everything other than D3D9) supports GLES1 as well.
ANGLE passes GLES1's
MustPass, however there are known missing features.
|Implemented through extensions 1
|Palette compressed textures
|Emulated with uncompressed format