Test in screen readers and see how content is being announced.
Lists have certain semantics which are very useful. Definitely good in navigation (aka nav > ul > li).
Grids are also useful BTW—we don't have specific "grid" tags in HTML, but using ARIA attributes you can set up grids which might map onto div tags or even custom elements.
Personally, I'm much less concerned about ul/li than I am "div tag soup" which is a plague upon modern web development. Use div tags sparingly, and almost always see if you can reach for either (a) a more semantic HTML tag (e.g., key/val pairs should probably be dl/dt/dd tags, not list tags), or (b) custom elements…yes, authoring tags with one or more hyphens which are purely for developer comprehension and hanging CSS off of is perfectly fine—recommended in fact—and in some cases if you need some JS component logic as well, then boom you have web components.