As for the SFMC part of the question, yes you can synchronize the Individual object since some, rather recent, version of the MC Connect app. This was not always the case, so valid question in my view. It's in Data sources / synchronized like the other SF objects:
This automatically reproduces the Object / table connections from within SFSC in an attribute group within the BU that the connector is in, typically Parent BU.
So, in that particular BU you do not even need to create the attribute group, it will be created for you.
In other BUs, you can reproduce the object relationship by querying the data into Shared DEs and setting up attribute groups with those, considering the delay that the querying automation that runs hourly at best will entail.
Can you do other things with the individual object? Yes.
Is it a good idea? depends.
You probably won't get a definitive answer here, but there is good official material that is recommended reading, e.g. starting here. Due diligence and applying such information to your particular scenario is something you have to always do yourself: