What i learned from all the color management sites and articles is:
You're document is in a device neutral profile ( srgb, AdobeRGB, prophoto,...)
Youre device is in the profile provided or your own made profile. Or choose the profile that is generic for your device.
Modern ipad pro choose p3, srgb, AdobeRGB, or the one you made your self.
The color management system in your device convert automatically the colors to and from the diverent parts.
You only put a device specific profile to a document when the (external print service) provide you a specific profile. So he can process the file directly.
To check the outcome of a profile you can softproof the document with the provided profile.
And yes you will see different colors on a ipad pro with a p3 gamut and a desktop monitor with a srgb gamut.
Greetings Ron Cromberge