Unfortunately not, it is the whole Compiler and VM. I'm not super familiar with embedding Luau only having messed around with it for a bit, but I highly doubt it'd be too difficult to drop in Luau over top an existing Lua implementation
Mostly that Lua datatypes don’t always have great analogs in TS (particularly tables) and you have to be pretty cognizant of what’s going on under the hood.
I'd love to have type annotations in Lua.
But this doesn't compile to Lua, right?