Well, it's hard to say for sure. They could be related through a shared universe or a crossover event. Or perhaps they have no direct connection at all and just exist in separate manga contexts.
There were a few novels related to the chainsaw man that could be recommended. One of them was " Chainsaw Man: I Have Two Divine Powers ", written by Stupid War-chan. The story was about the protagonist, Kotone Shallow Feather, who had transmigrated to the world of the chainsaw people and obtained the power of the Divine Eyes. The other was Chainsaw Man: I Have Two Demons, written by Thirteenth Wang.
" Saw 9 " was the latest movie in the Saw series, directed by Darren Lyn Bosman. The film continued the plot of the previous film, continuing to tell the story of Jigsaw's trial of those who did not value life. There was no specific information about Saw 10 at the moment.