Hi,
I'm experiencing the same issue. There is no support for Enterprise login using OAuth2.0 via ArcPy.
We use Arcpy to overwrite feature layers to automate the refresh but because it doesn't support Enterprise Login via ArcPy, I need to sign in manually and check the 'Sign In Automatically' option in ArcGIS Pro.
However, for whatever reason, sometimes the user gets signed out of ArcGIS Pro which causes the script to break.
Would be great if there is an option for me to pass a token of some sort through ArcPy.
arcpy.SignInToPortal(arcpy.GetActivePortalURL(),token='')