The Wonderful Flight to the Mushroom Planet, my favorite early-childhood book was The Space Ship under the Apple Tree (1952), by Louis Slobodkin. Like The Wonderful Flight, it involves a passionate same-sex friendship.
A boy scout named Eddie Blow meets Marty, an alien boy his own age, and exclaims "Let's be friends." Marty doesn't know what "friend" means, so Eddie shows him.
They become involved in the search for Secret Power Z, which will allow Marty to return to his home planet.
There were four sequels, but I never encountered them.
Born in 1903, Louis Slobodkin wrote over 50 books, mostly children's books, including One is Good, But Two Are Better (1956), Melvin the Moose Child (1957), and Luigi and the Long-Nosed Soldier (1963). They sound like male friendship is emphasized, making them part of the repertoire of gay kids.
He was also an illustrator, and of course a sculptor who specialized in the male form.
Could he have been gay? Maybe, maybe not. Same-sex friendships were commonplace in children's fiction before the 1980s heterosexualization of childhood, and he was married to children's book writer Florence Gesh. But that statue of Lincoln with a massive chest and phallic hoe. . . .