In my opinion, it's highly unlikely. Goku has mastered multiple forms and techniques that give him a wide range of powers. Saitama's one-punch style might not be effective against Goku's diverse skills and battle experience.
I don't think there's a clear winner. Both Manga Goku and Manga Saitama have unique and powerful abilities. It could come down to strategy, luck, or even the author's imagination!
Another theme could be the clash of different universes. Amazo is from the DC universe and Saitama is from One Punch Man. Fanfics might play around with how these two different universes' rules and powers interact when these two characters meet. Also, there could be themes related to respect and rivalry. Saitama is often very nonchalant about his power, while Amazo is a complex android with various abilities. How they view each other in the fanfic can create interesting storylines.
Saitama would win. He has shown incredible strength with just one punch. His power seems limitless, and in a fanfiction scenario, his simplicity and raw power would likely overpower Jiren's more complex abilities.
One possible plot twist could be that Jiren discovers a way to nullify Saitama's strength. Maybe he finds some sort of energy - draining technique that weakens Saitama over time. Another could be that Saitama holds back for some reason, like he wants to see the full extent of Jiren's power, and in doing so, he gets into a real struggle.
Once in Gacha Life, there was a girl named Lily. A group of mean characters would always make fun of her unique outfits. They would laugh and call her 'weirdo' whenever she entered the virtual schoolyard. One day, Lily decided she had enough. She started to focus on making real friends who liked her for who she was. She found a small group that loved her creativity in dressing up her Gacha character. Eventually, those bullies saw how happy Lily was and they stopped their mean behavior.
There was a Gacha Life love story of two characters, Rose and David. Rose was a bookworm and David was a sports enthusiast. They met at a club fair where David was trying to promote the sports club and Rose was looking for a reading club. By mistake, Rose walked into the sports club area and David kindly showed her the way to the reading club. After that, they kept running into each other. David started to borrow books from Rose and Rose would go to watch David's sports games. Their different interests brought them together and they fell in love.
A sad Gacha Life story could be about a character who loses their best friend in the game. For example, they might have planned to build a virtual world together, but then the friend quits playing. It makes the remaining character feel lonely and sad.
Once in Gacha Life, there was a character named Lily. She was always left out by the other characters in the club. They would go on adventures and have parties, but never invited her. Lily would sit alone in the corner of the virtual schoolyard, feeling so sad and unwanted. It made her virtual heart break every day.