If you've got a decent enough connection, it's honestly not as detrimental as you might think. I played on Stadia from its launch day up until it closed earlier this year. I was able to fairly consistently place top of the scoreboard in my cross-platform PVP matches in Destiny 2, during both the skill-based and connection-based matchmaking metas. I think I'm something like 500+ miles from the closest Google datacenter, too.
In Europe good connected homes (basically cities) can have a ping of 10-20 ms. Most people won't notice mich of a lav when they casually play on their couch.
Yeah was getting 3ms for stadia. GeForceNow is 15ms right now. During game play there is absolutely no fealing of lag at all. The only way to notice it is to move a mouse in cricles in the menus, where very slight ruberbanding can be felt.
If the service is decent enough with servers close by, it really isn't bad at all. In a PCgamer test, the input latency for Metro Exodus and Destiny 2 went from 46ms and 51ms local to 96ms and 75ms from GeForce Now, and 179ms and 129ms from Stadia.
It can be surprisingly decent depending on your connection. I've wirelessly streamed VR from my home computer in another city and it was very comfortable and playable.