Sounds like you are want something like “if the user is allowed to read objectX, then activityX, else activityY.
Can you retrieve security settings? No, you can not. Mendix has not built any public available tricks for this, probably because it would make the security settings far too transparent.
But in a microflow you can retrieve the userroles that a user has:
And you can check if a user has a certain userrole by using the userrole-tokens:
This might help you on your way.