Assume you don’t need a super duper PC but a fast internet connection or is that a console type thing ?
Thats the crazy thing about it, it runs on anything that can run Chrome.....Including my work laptop, which is so bolted down interms of 'managed' software I cannot even run Excel Macros without getting permission, yet Stadia works on it!
You do need a good internet connection, Stadia website says something like 10Mbps, but the experience will be awful. On any of the laptops, streaming at 1080P, I'm seeing download rates of 25-30Mbps, and that's sustained - constant download rate unlike normal streaming video where you see a high initial peak and than it settles.
If you are using a ChromeCast and link it to a 4K capable TV, even at 1080P the download rate is 50Mbps+, peaking to over 60Mbps. If you stream at native 4K (for which you have to pay an subscription to Stadia Pro for), I suspect you will need download rates close to 100Mbps peak and easily 70-80Mbps sustained.
So the trade off for not needing expensive hardware to run games is the need for fast internet. If you do have fast internet, its very very good. I cannot tell the difference between playing games on Stadia, versus using my Xbox or any other local device.