I am looking into being as hardware agnostic as possible with a new AR app, and I would like to support at least HoloLens and Mobile. Are there any good ways of doing this today?
For instance, would Vuforia help me achieve this goal?
Would it be hard to “manually” support HoloLens and Mobile without using a framework like Vuforia?
Greatly appreciate any feedback 
Did you find any resources on this?
I believe you can achieve this with Vuforia. It will work for both HoloLens as well as mobile devices. But I’m not so sure about this - for deploy to market, you might need to use different keys generated from Vuforia (need to re-confirm on this). We were implementing similar one for Tango and HoloLens. But the real problem comes in platform specific UX changes/codes. I would prefer separate projects or having separate scenes for different devices (HoloLens and Mobile) and set the scenes up according to the build settings.