There are no such inappropriate 'Straight Shota' stories in the official Dragon Ball Z canon. Dragon Ball Z mainly focuses on epic battles, power-ups, and the adventures of Goku and his friends to protect the Earth from various villains.
One alternative is to focus on character backstories. You could write about the early days of Piccolo, how he came to be the way he is. Another option is to do crossovers with other non - sexual universes. Maybe a story where the Dragon Ball Z characters meet characters from a magical anime world and they have to work together to solve a problem. Also, you can write about the relationships between the characters in a platonic way, like the deepening of the friendship between Gohan and Krillin.
A Kryptonian in the Dragon Ball Z universe could potentially be a very powerful addition. Their natural abilities like super strength, flight, and heat vision could make them a force to be reckoned with. However, they would also face challenges as the Dragon Ball Z world has its own power scale with ki-based powers. They might have to adapt to the different fighting styles and power sources. Maybe they could learn to use ki in addition to their Kryptonian powers, or they could find a way to combine the two in unique ways.
Dragon Ball Z is both anime and manga. The anime was adapted from the manga and they share the same story and characters, but presented in different mediums.
One interesting crossover could be a battle between Hulk's brute strength and Goku's Super Saiyan power. Maybe in the fanfic, they start off as rivals, with Hulk misunderstanding Goku as a threat to Earth. Their fight would be epic, with Hulk's limitless rage against Goku's increasing power levels. It could also explore how their different universes' power systems interact.
In addition to the first chapter of the Dragon Ball series, Dragon Ball Z, and Dragon Ball MT, there are the following chapters:
1 Dragon Ball Alpha: This work was an adaptation of the Dragon Ball series of comics and was released in Japan in 2009. The story was set in a different universe from the Dragon Ball series, and it mainly talked about the battle between the protagonist Gohan and the Great Demon King Bick.
Dragon Ball Super: This is an animated adaptation of the Dragon Ball series, released in Japan in 2017. It was one of the most popular works in the Dragon Ball series. It told the story of the protagonist Goku, Super Gohan, Vegeta, and other people's power upgrades.
3 Dragon Ball Defense: This work is a mobile games adaptation of the Dragon Ball series, launched in Japan in 2016. It was a tower defense game where players needed to defend the Dragon Ball defense tower to prevent the attack of evil forces.
4 Dragon Ball Ultra: This is an animated adaptation of the Dragon Ball series that was released in Japan in 2020. The story was set in a different universe from the Dragon Ball series. It mainly told the story of the protagonist Goku and Vegeta fighting against the evil forces.