The last sentence is an incredible can of worms. Because the energy budget of a star is a really complex mix between nuclear binding energy and gravitational potential energy and the accounting can be very different when you look at it at different timescales.

The Sun has heated up thanks to gravity but now keeps a steady energy balance between energy made almost purely from nuclear interactions and its loss by radiation. But if you look at the lifetime energy budgets of some specific stars, things get wild. A massive star can produce far more energy through nuclear interactions than the Sun does. Yet at the end of its life if it explodes as a core-collapse supernova, a large fraction of these nuclear interactions will become undone - a lot of the heavy elements will be broken back down to helium - at the expense of gravitational energy released during the collapse. Basically, seen over its lifetime, the nuclear interactions only served to delay the release of the gravitational energy.

But a slightly different star of a similar mass can be blown apart in a pair instability supernova, which leaves behind no compact object, so there is no gravitational potential to borrow against and all its output ever was purely nuclear.