Undertale is a weird one; it’s probably a jrpg, by this definition. I get what you’re saying, but there’s really just 3 paths through the story; you don’t have any real influence over what happens on each path aside from choosing which one to follow. There’s no dialog trees or decisions to make (aside from, obviously, which ending you’re pursuing), and character interactions are handled via static dialog or cutscenes. It feels like there’s a lot of player agency but in reality, you’re either completing a checklist for ending A, completing a checklist for ending B, or you’re getting ending C.