Its been some time sense I’ve opened Pythonista… Figured out a way to download youtube videos on my ipad with a custom script I made in pythonista. and published a video on how I was able to do it… and received my first youtube strike 
but that was ~ 2yrs ago… was able to get plotly working but not sure about dash… You can make dash apps mobile friendly and I believe you can turn them into actual apps on the IOS or android market place. However… I’d highly recommend not using pythonista for the actual IDE for building anything serious, I think pythonista is best for downloading jupiter notebooks or simple projects and reviewing them on a trip by plane or car for some quick mobile learning. Get a proper PC or if that isn’t available look into cloud hosted solution like https://py.cafe.
Quick extra tip for developing and testing dash apps on mobile: How to Develop and Test Dash Applications on your Phone