I did exactly the same, starting from the repository on GitHub. Though chat though me it was used outside Roblox, but without giving me examples.

Gideros is an interesting case, seems like they already added / modified features while using Lua and had to replicate those changes supporting their own version of Luau.

Personally, I would prefer to stick with regular Luau to benefit from regular improvements and be able to contribute back to the project eventually.