Would be interesting to get a nice web cam too but that is less important to me. I'm also not a huge "thinness" type, thicker is fine if it isn't heavier.
I suspect if all of what you listed are actually hard requirements, the only way you'd ever get that is if you built your own - source an industrial 4:3 panel+controller, find the smallest Ryzen board with ECC support and get a Ryzen Pro APU (none of the ThinkPads will boot ECC SODIMMS on their boards, despite Pro APUs having nominal unvalidated ECC support) - you could try your luck with an A320TM or otherwise, might need to go embedded Epyc and an M.2 display adapter (like the SM750 ones). You could probably build a "tablet" form factor that's reasonably thin (<30mm?) and light (and use an external USB-C PD compatible chargers/battery packs and simple DC conversion to make life easier on the power side).
With Dell at 17” and paid Linux support you have to move to the Precision line.
I wish Dell would just have a single line of quality Linux compatible laptops you could buy off the shelf and know would always work.