I wouldn’t do this personally because the downstream code very often has to handle differences where polymorphism breaks and you end up having to query the type. Polymorphism shouldn’t be used for data, only behavior, and only in very specific circumstances. Subclassing is a different topic.

Definitely don't want to store types as columns in a DB, especially because of the inevitable thing that qualifies as two different types. In this situation, I'd usually take the first one (nullable cols) without much consideration. The DB doesn't need an xor constraint, but it can if you really want. New cols can be added without much impact on existing data.

And if the info is non-scalar, it's either option 2 (nullable FK) or 5 (JSON), depending on whether or not other things join with fields inside it.