I second the idea of a T480, it’s what I use. I threw Linux Mint on it and never even think about it, but if you want to use Windows, then I see no reason why it wouldn’t run perfectly well either. Looks like they go for $120-200usd depending on configuration. I spent over $300 a year and a half ago, and I would still consider that a good deal, so $200 is a bargain imo.
The Steam Deck adds something incredibly valuable that the PC market has never had: a consistent target spec for minimum hardware requirements. Upgrading every couple years would create confusion for which version for developers to focus on. They are treating it like a console, not a PC.