It barely worked in their web client but the desktop client worked pretty well.
The cost ended up being around 1€/hr when the instance was on, and 0.06€/day for the storage. I am sure this could be optimized (e.g. use snapshots and spot instance) - but I just couldn't be bothered to. For me it is worth it.
Seems that it would work quite well for turn based games (including auto save)
Stadia, GeForce NOW, Xbox Game Streaming and PlayStation Now: I've tried them all, and GeForce NOW specifically is very good. But, they only allow me to play a subset of my large pre-existing game library, and/or make me buy games again, which I'm not interested in.
Stadia is specially bad at this, having to purchase on a game-by-game basis, not being compatible with any existing ecosystem (Steam, PS, Xbox have cloud saves and friend lists), and then trusting Google to run my game forever on their servers after paying a one-time cost.