It should run fine in either Android or iOS using any browser. We can look into that further.
However, I really don't recommend using Blockly on a phone. The small screen is extremely frustrating. It may end up doing more damage than good, in teaching kids that programming is a terrible experience. That said, if you have tablets, then it's fantastic. It's all about the size of the screen.
This advice is common across all the educational programming options. Blockly, Scratch, App Inventor -- we are all interested in phones, but nobody's been able to create something that works well on those tiny screens.