From 2018 to now there has been a significant improvement in laptop processors (TDP 15W-45W).
However from 2012/13 to 2018 the passmark combined score was only double at the same TDP, or the equivalent power from 45W TDP to 15W TDP, see: Intel Core i7-3840QM @ 2.80GHz vs Intel Core i7-8750H @ 2.20GHz vs Intel Core i7-8650U @ 1.90GHz [cpubenchmark.net] by PassMark Software.
The main performance gripes are:
limited to SATA6/USB3 speeds for the storage-drive (it’s fine but modern NVME PCIE speeds would be nice).
X230 and T430 limited to 16GB RAM (it’s fine but 32GB would be nice).
Modern CPUs no longer use S3 sleep, and AFAIK Xen still hasn’t migrated to whatever intel calls their modern suspend (I’ve forgotten the name).
Heads is compatible on a limited number of laptops. If you know somebody familiar enough with coreboot who could port Heads to a modern laptop, let me know (but I doubt it will be cheap).
Coreboot is also only compatible with a limited number of laptops, porting to new boards is not a trivial amount of work.
Given old thinkpads use 18650 cells, you can recell them and get a 100wh+ battery, meaning the battery life of an old thinkpad with 35/45W cpu can be comparable to a modern laptop with 12-28W cpu.
Security & Bloatware:
Even if you could port Heads to an existing laptop, why would you?
Modern Intel CPUs cannot have the Management Engine removed (at-least that is documented anywhere publicly), at the very best it is: ask nicely to disable.
See, https://twitter.com/markel__ for prime examples of how each new generation of Intel CPU is just more vulnerabilities and bloat.
And for AMD’s PSP, well: who knows?
These are the core concerns AFTER you’ve:
factored for all the new chips/computers on your motherboard with their own firmware
the need for newer linux kernels with more bloat, simply for compatability
I would like a modern, reasonably secure laptop. And it is possible. However it would have a radically different design from anything currently on the market. (If you know anybody experienced with supply chain, let me know).
I can still install QubesOS with hardened Xen and minimal kernels on modern laptops which are compatible. (Though with the disclaimer that models in the past couple of years may not suspend/hibernate properly due to the aformentioned Intel migration from S3).
I can also flash pre-built coreboot images onto compatible devices (but I’m not willing to port coreboot it’s not an area I’m familiar with and either-way I know that the time required is not worth the money people are prepared to pay).