Yes. Oxygen is the heaviest element capable of being created in the fusion reactions in the Sun. Generally, the heavier the element the more massive a star it takes to produce it. The Sun is a main sequence star. Its mass is quite average. At the end of the Sun's life cycle after its red giant phase, carbon and helium will slowly fuse into oxygen. Oxygen will no longer fuse in the Sun. The remnants of the Sun will be left to cool off as a white dwarf. The cooling will happen very, very slowly over billions of years due to the extremely high density of the dead star.
There is oxygen detectable by spectroscopy within the sun's plasma created through nuclear fusion. The sun uses nuclear fusion to create more massive atoms while extracting energy in the process. In the sun's core, 4 hydrogen nuclei can fuse together to form the isotope helium-4. Two helium-4 isotopes can later fuse into one beryllium-8 isotope. Later in the fusion cycle the beryllium-8 isotope can fuse with another helium-4 isotope to create one carbon-12 isotope. Finally, to get to an oxygen-16 isotope in the fusion reaction a carbon-12 isotope fuses to another helium-4 atom.
Difficult question, Never gone there, LOL !!
The sun is not a big lump of fire like fire on Earth. Light and heat from the Sun come from nuclear fusion reactions that convert hydrogen to helium. From that reaction there is heat with very high temperatures.
Sun Does not need oxygen to produce heat, so the Sun does not burn. The heat produced by the Sun does not come from an oxidation reaction, but rather a fusion reaction. The fusion reaction is the process of combining two "light" atoms into a more "heavy" atom. The main constituent of the Sun is hydrogen. Hydrogen atoms are "light" atoms.
The Sun's body contains extraordinarily high pressure so this pressure forces two hydrogen atoms to join (fusion) to form helium atoms that are more "heavy" than hydrogen atoms. However, in this fusion process, not all hydrogen atomic particles are used to form helium atoms. Some of the hydrogen atom particles become energy or energy sources.