Did Lenovo push the current Debian to your device? Have the apps when you bought your laptop increased in resource use by an order of magnitude?

It's not the same kind of device running with the same constraints. Phones were pushing the limits of miniaturization. The difference in the underlying technology is vastly different. Comparing a laptop from 2002 trying to run the current Debian is more apt.

I don't understand what you're getting at. I bought this X220 about a year ago on Craigslist for $100 and installed Debian on it. The main app on it whose resource use has bloated a lot since 2011 is Firefox, and that's a persistent sore point for me, since it's the web that has bloated rather than just the browser. The other stuff I use (mostly Emacs, Python, and Xchat) hasn't really bloated. I have a Thinkpad X40 (from 2004) that I used for similar purposes but its hardware eventually got too flaky.

I would say I keep a lot more data on the X220 (using a 0.5TB SATA SSD) than I could store on the X40 which had a 40GB PATA drive. It had USB2 and SD card ports though, so I could in principle have added a high capacity SD card or whatever. The X61 of the same era is still a viable machine and I think it had a SATA drive slot, which means it would be pretty usable with today's ssd's.

I am sure you get Lineage OS, or something like it to run great on an old phone, just as I am sure you installed Debian yourself.

Mostly when we are talking about phones getting upgrades or not getting upgrades any more it is about updates from the manufacturer, so I don't see where you are going.

I think that is not so easy but I haven't looked into it too much. Only a limited set of phones work with it and I think their functionality is also limited. I do have a Nokia N900 from around 2008, but despite its coolness it has never really been usable (too slow and too small).