This has been quite a lot of fun conjecture but I am in a position to tell you who the science fiction author Gavin Hyde was, because I knew him; in fact, he was my half-brother. Very nice guy, smart and eccentric, spiritual, and he did play chess, yes. He also played Scrabble competitively when over 70 years of age. He was born in 1930 in the US and died in 2019. I was at his Montecito memorial near Hyde St.... Hyde, yes, the family had been prominent.
His father, mother, grandfather and grandmother all were born in the US. The family was based in Santa Barbara. His father, married three times, had also been a writer and his grandfather was an illustrator, antique dealer, and was active in Santa Barbara civic affairs. Gavin's paternal grandmother hosted a literary salon in her Santa Barbara home for local writers.
Gavin likely quit writing stories because his life itself was more or less performance art, so it was full of so many other things to do. (E.g., for an extended time as a young man, he lived in Spain.) Some of the family (including Gavin), were bohemians, then beats, then I guess you could say some were hippies and some not, but always with an entrepreneurial side. Gavin's and my father Bobby Hyde started the Mountain Drive artist colony in Montecito.
You are dubious, I'm sure. Gavin would have found this all to be quite hilarious and probably would have been flattered that you thought Bradbury wrote his works. Just a thorough search for the titles would have led you to this UCSB link with some bio info about Gavin and also his father Robert (Bobby) Hyde, who had five children of his own, plus a bonus child who was out of the picture (me). Additionally, he raised/fostered 8 other children.
And since you are into sci fi, check out the serious sci-fi film Seconds with Rock Hudson, which was filmed partly at said Mountain Drive colony---the hot tub scene, a bit exaggerated for the sake of the plot. Ah, now you are starting to believe. This will answer the rest of your questions.
Robert Hyde was also known as Bobby Hyde, and info on him and Robert W. Hyde, our grandfather, is also easily found online by including the search phrase Santa Barbara. Enjoy.