It all depends if you consider basically all non web GUIs developed the last 40 years or if you limit yourself to reactive web UIs developed the last few years. Tongue in cheek :)
Sure, reactive frameworks in js that mainly operate on the DOM/HTML/CSS stack may be very little OO, but Swift/Dart/Kotlin are OOP languages and Flutter for example, while using a reactive model, is still 100% OOP with Widget classes in a composition and so on.
Sure, reactive frameworks in js that mainly operate on the DOM/HTML/CSS stack may be very little OO, but Swift/Dart/Kotlin are OOP languages and Flutter for example, while using a reactive model, is still 100% OOP with Widget classes in a composition and so on.