Oh, I get it. It's like a tech demo, to encourage Microsoft to add compiler plugins. Can't really use it on a project of any scale, due to every other tool also providing its own TS compiler, again because TSC doesn't support plugins.
I use it in the code generator mode (https://typia.io/docs/setup/#generation) that doesn't require the tsc plugin integration and works well with other build tools (in my case esbuild) and arbitrary testing/code-coverage libraries.