You have my attention. I assume this would also work well on a worse laptop (since the processing is done in the cloud)?

I use boosteroid, which is just steam on cloud. ~4k @ 120Hz for $12/month. No HDR though (they recently removed it). Such a stupid good deal compared to the price of a gaming PC, that I can't really complain. So many data centers with GPU sitting around...

Yes, it's just streaming a video to you. The main limit is your connection speed if you're not near a datacenter as you're limited by ping, so controls can be laggy. You can try it out for free though, which will give you an idea of how good your link is.