As such it means you may not be very familiar with the genre.
Visual novels usually are played in first person perspective. You hear dialogue of the character whose actions you currently affect.
A lot of visual novels feature bad endings. Some of the bad endings result in protagonist’s death, which can be sometimes very horrible. Some games make fun of that and give you an achievement for collecting all 25 bad endings, for example.
In a scenario where there are no bad endings, usually the main motivation is to either figure out how to get to the “true ending” route, which can be very difficult, or direct the game into the route you want (especially if it is the kind where you want protagonist to win over a specific character). Even in this case there’s usually “default route” which means you’ve messed up and lost.
With that in mind visual novel works simiraly to a puzzle game - you analyze the story/behavior and try to discern choices which will lead you to the desired outcome.
In addition to that, there are hybrids. For example, there are visual novels that use turn based strategy segments. I saw gameplay similar to europa universalis (meaning map painter part of Total War) in a few titles. Then there are games with mecha combat.
One example of such hybrid is Sakura Taisen series. Visual Novel segments + minigames + turn based non-grid mecah combat. Then we have disgaea. Persona games also have very strong visual novel elements.
In addition to unlocking route extra motivation is collecting character and event artwork.
The separate thing from this is kinetic novels, those really do not have any choices. Examples include Karakara games on steam (which I ALSO haven’t played) However, I think even those cases it is “interactive entertainment” somewhere halfway between a game and a movie.
Either way, the normal time to beat a visual novel is around 40…60 hours to unlock everything. It is kind ahard to claim it is “non game” at this point. Also I think the right idea is to treat “visual novel story progression” as a gameplay mechanic, which can be combined with many other mechanics to create something.