I try to find some apps for indicators. To alert me when indicators for some coin reach some value but I could not find any apps for that so I am trying to create one.
I think trading view has that feature if you set it properly, I've tried it couple of times already in the past and it's seems okay. I think SMA should be your next target and yes Bollinger Band is a nice indicator to be added too.
Its available in trading view and exchanges also have this option, if OP is looking for a more advance application when it comes to using indicators then I think there is no app yet but hopefully