> fit their custom hardware, eg. a TPM designed for user security instead of vendor lock-in.

Just here to point out that they use a standard commercial off-the-shelf TPM manufactured by Infineon. It's not custom hardware. As with all TPMs, it is the firmware/OS that decides whether to use it for lock-in purposes or freedom.

I think the firmware is custom (and of course it’s the nexus of hardware and software, so exactly the part that OEMs can best provide the user unique value through. System76 and Pine64 (and I think Purism) provide open source firmware you can reflash yourself for custom keyboard layouts, firmware killswitches, etc., though System76’s hardware itself seems very off-the-self (Clevo white-label). (Edit: And I think Purism Librems overall design with hardware killswitches, etc. are custom ofc.)

Lenovo talk a good game, but I have thus far been unable to find a linux laptop available for purchase on the lenovo site.

I don’t think they ship anything with it preinstalled right now (unlike each of the other companies I and the parent mentioned). But they’ve had a reputation of generally good Linux support for a while now, and it’s seems they’ve just now decided to make it official, and there’s plenty of hope for preinstalled GNU/Linux in the future.

I'm hearing they will ship the P53 and a few other models with Fedora Workstation 32 by the end of the year: https://www.forbes.com/sites/jasonevangelho/2020/08/10/lenov...