I do not agree with ScreenRant's assessment that "Lightyear" is the story of a *Real* Person named Buzz Lightyear in the Toy Story world who eventually had toys and cartoons and video games made up around his exploits. (*Real* as in exists in the same world as Andy, His Mom, Molly, Bonnie, et cetera, and was someone they could meet and interact with directly, not a fictional Character to them.) The technology shown in that Trailer far outpaces anything seen in the Real world of the Toy Story films, which seems rather to just be like our own in terms of technological development. As another member pointed out, Stinky Pete clearly references Sputnik in Toy Story 2.
I think the idea that this is intended to be a piece of media that Andy and his Friends saw either as kids or a new movie about Buzz Lightyear that Andy would go see "now" as an adult makes much more sense than the idea that this is supposed to be the story of Real Astronaut/Explorer. Heck, it could also just be an entirely new reimagination of the Character and his story that is not intended to tie directly back into Toy Story and its narrative world, but rather just be Pixar getting to do a fun riff on one of their ideas and characters.
Either way I really don't think this is supposed to be a "True Story" in the Toy Story universe.