Yes, there are likely 'Bardock Kills Frieza' fanfics out there. The Dragon Ball universe has a huge fan base, and many fans like to create alternative storylines. You can try searching on fanfic websites like FanFiction.net or Archive of Our Own.
The plot could start with Bardock having a premonition of Frieza's future actions against the Saiyans even before the destruction of Planet Vegeta. He then secretly trains and discovers a new form or power that allows him to stand up to Frieza. When Frieza arrives to destroy the Saiyans, Bardock reveals his newfound strength and battles Frieza. After a long and intense fight, Bardock manages to defeat and kill Frieza, changing the course of the Dragon Ball universe. This could also lead to new alliances and power struggles among the remaining characters.
Well, it could be that in the fanfic, Bardock's group forms an unexpected alliance. Perhaps they team up with another powerful race or a group that has some sort of technology or magic that can counter Frieza. This alliance provides them with the means to not only fend off Frieza but also to ensure their survival. Another possibility is that there is some sort of time - travel or dimension - hopping involved. They could escape to a different time or dimension where Frieza can't reach them.
In a 'Bardock's group survive Frieza' fanfic, a major element is the alteration of the power balance. This can be achieved in multiple ways. For example, the fanfic might introduce a powerful artifact that boosts the Saiyans' power. The relationships within Bardock's group are also important. If they have strong bonds and are able to communicate effectively, they can better coordinate against Frieza. Moreover, the fanfic may explore different Saiyan cultural elements that give the group an edge. For instance, a long - forgotten Saiyan ritual or knowledge that helps them in their fight for survival.
He could meet his descendants like Goku or Vegeta. It would be an interesting encounter as they have different upbringings and personalities compared to Bardock.
Frieza might initially be shocked. He's used to being a feared and powerful being, and the idea of having a family is very foreign to him. So he could be in denial at first.
Often, Goku is paired with Bardock. Since they are father - son, it makes for an interesting dynamic in the fanfic. Bardock can see how his son has grown and influenced the universe, and Goku can learn about his Saiyan heritage directly from his father. Another character could be Vegeta. They can bond over their Saiyan pride and work together to protect the Saiyan race or take on common enemies.
For Yamcha, you can focus on his growth from being a bit of a comical character to a more serious and respected fighter in the context of his relationship with Frieza. Maybe he learns from Frieza's cold and calculating nature how to better strategize in battles. For Frieza, his development could be about him learning to care for someone other than himself. He could start to see Yamcha as an equal, which is a huge shift from his usual superiority complex.