There shouldn't really be any porting required. These are just (supposedly) powerful PCs running the game server side. Unless Stadia is using some crazy OS, it should run like the PC equivalent. Instead, it's running worse than the higher end consoles. My guess is their infrastructure isn't ready to do real-time 4K streaming.
But, more importantly, it's freaking Google. They should have had this shit ready to go if they wanted to prove themselves in the serious gaming market.
The Stadia OS is linux based, not Windows.
Massimus - "Trump already has democrat support."