I think that's too granular and is dependent on the apps offering Face ID as a secondary-layer authentication flow -- I think OP is suggesting an entirely different user profile that doesn't even have the same applications that the original (save for the default iPadOS apps, and even those should be logged out from your Apple ID). The cognitive overhead of "did I make sure to enable Face ID on x,y,z apps so that I can pass around my iPad without worrying about any personal data being accessible" is too high for spontaneous + casual device sharing.
Example:
"Hey uncle ping00, can I use your iPad real quick to watch something?"
"Sure nephew, <switches profile to Guest ,and hands it over> go nuts"
Example: "Hey uncle ping00, can I use your iPad real quick to watch something?" "Sure nephew, <switches profile to Guest ,and hands it over> go nuts"