Add ability to use custom "User-Made" template in Excel
Add support for CUSTOM TEMPLATES in mobile version of excel. Another question asking the same thing was posted, but apparently Microsoft can't read as they just added the ability to use templates, but not CUSTOM USER-MADE TEMPLATES! Quit handicapping your mobile apps. It's bad enough form controls and VBA aren't supported still. At least make a useable option that is mobile friendly.
Even Google sheets can open xltx files..