One way to look at it, but consuming OOP libraries doesn't turn code into OOP.

Also, FSharp.Core (which most F# code leans heavily on) is not OOP at all.

F# promotes object programming, doesn't proscribe mutability, encourages function and data approach.

It offers simple access to the different paradigms, with some opinionated choices (e.g. preventing leaning on OOP beyond an arbitrary stretch, like no "protected", only explicit interface implementation, etc.).