I'm in the market for a Linux friendly ultralight laptop to check web apps and run terminal, nothing fancier then that. Do any cheap systems exits these days? I was looking at a chrome book but apparently the mediatek chip doesn't play nicely with FOSS.
I prefer the T480 series (imo Thinkpad went downhill from there onwards). The non-s is a great off-road laptop, but for what OP is asking, the T480s seems like a more sensible choice.
What about something like the Thinkpad X201? It's not ultralight but it is quite small.
Other than that I'd probably say a Chromebook with a Linux install. Second hand they are quite cheap and can likely do what you are after. A lot of them have passive cooling which is nice for a couch device. I was able to install libreboot on my C201P quite easily and now it just runs a traditional Linux install
I'm writing this on my x201 on my couch. I love it, but it's not a great couch laptop. It's kind of heavy, runs hot, and has poor battery life vs more-recent comparables.
I used to have X230 as a daily driver for laptop (I got separate desktop) and it's a really nice machine for it's size. Only the display is a bit lacking by todays standards as it's only 1368x768, but for 150€ (give or take) it's not too bad.