How much Visual Studio can be replaced by InteliJ, depends on the underlying programming stack.

If it is to write Windows games in C++ that are then consumed in Linux via Proton, is a kind of Phyrric independence.

Who pumps the money into the Typescript team, and calls the shots on its evolution?

Naturally you can have your own compiler and trail behind its development, with the sponsorship of the likes of Vercel or Anthropic.