Hi, I know this game jam has an emphasis on VN and storytelling, but would it be acceptable to include other elements (i.e. farm simulator, shooting, RPG mechanics, puzzles,etc) but still use VN format to convey a story?

Almost like how Danganronpa is classified as a VN but has a free roaming, relationship forming, puzzle mystery aspects to it. Not saying Im plan on making a mystery thriller or open world sim, but could I incorporate other mechanics to complement a traditional  linear/kinetic VN?

How apparent does the VN aspect have to be?

Everyone's feelings are going to be different on this, so for a sort of nebulous answer:
If you'd sell it as "a visual novel with puzzle elements" (999), versus a "puzzle game with visual novel elements" (Professor Layton), then it's a visual novel.

As a personal opinion, I think at least 50% of the gameplay should be visual novel component for it to count in this specific instance.