I can find games, window managers, embedded devices, and a bunch of other stuff that can be scripted with Lua, but there doesn't seem to be anything like a Visual Basic equivalent that lets you layout a GUI graphically and tie the controls and events together with Lua, at least not for native applications. Why is that? It seems like it'd be a good fit.
For Lua, it's use as a mainstream application development language is still in it's early stages. The language follows the mantra of move fast and break things so backwards compatibility isn't a top priority and this can be an issue in evergreen codebases like web apps (unless you are willing to lock to a specific version). Most web servers (most famously OpenResty, a Lua NGINX hybrid) are still on 5.1 due to LuaJIT.
Basically, my interest in Lua is this: I'd like to build a personal computing environment that is oriented towards end-user empowerment the way I remember them being in the pre-web era. To that end, employing a relatively simple interpreted language to build as much of the environment as possible is desired such that the end user is able to read and modify large portions of it, as well as create their own tools. Something on the level of Visual Basic or HyperCard would be useful for the GUI portions, and Lua is popular enough to have a lot of learning resources available, so it was an option I was considering.
There have been quite a few attempts at building OSes with Lua as main system/userland language. There are very few Lua implementations that can bootstrap so you still need a bit of non-Lua code as glue for the interpreter bits if not for juggling pointers.