"There's nothing there" is pretty close. I see OOP as fundamentally one key concept: that there are functions which "belong to" specific types, and all other operations on those types go through the functions that "belong to" them.

You can do OOP in a language like C by writing your code as structs and accompanying functions that operate on them. You might expose the structs to the rest of your code as opaque pointers to enforce that all other code has to go through these accompanying functions to use this struct. Or you might just make it be convention. An OOP language is just one that has language features to facilitate this, such as by allowing you to define methods within a type rather than functions outside of it.

Once you have this, then you might start thinking of features that might be nice to have alongside, such as dynamic typing, dynamic dispatch, inheritance, etc. But I don't think any of those are fundamentally OOP, they just fit well and are often found together.

Since having functions that belong to specific types isn't a very big concept, discussion about OOP is going to focus on these other things, which are not necessarily omnipresent and are often different across languages. So the discussion is either going to be very specific to one particular language (maybe even one particular set of libraries for it) or very vague.