I'd love one of these with a much better screen and some light ARM CPU. Has anybody tried to stick a Raspberry Pi 4 and an iPad Pro screen (or something else with a matching aspect ratio) into one of these?
No ARM CPU, but there was an aftermarket conversion called the X62[0], with upgraded display and Intel Broadwell CPU. I think it's mostly been supplanted by an X201 conversion, the X210[1].
[0]: https://geoff.greer.fm/2019/03/04/thinkpad-x210/
[1] http://www.cnmod.cn/x210/