1. Buy a cheap laptop with a replaceable memory and nvme slots and upgrade them for cheaper than you could buy them for. Dells typically have replaceable memory and nvme drives.
2. Buy a cheap laptop and put a 1TB NVME drive in a Thunderbolt 3 / superspeed 10 enclosure. This would be the way to go for a Macbook Pro.
If you're going to do superspeed 10 (~ 1 Gigabyte/sec)
NVME disk: https://www.amazon.com/Crucial-1TB-NAND-NVMe-PCIe/dp/B07J2Q4...
SuperSpeed 10 enclosure: https://www.amazon.com/Plugable-Tool-free-Enclosure-Thunderb...
If you want to do something faster (3 to 4 Gigabytes/s) than you should look at the Samsung Evo/Evo Plus/Pro nvme sticks and a proper Thunderbolt 3 enclosure for NVME like this one:
https://www.amazon.com/WAVLINK-Certified-Thunderbolt-Enclosu...
FWIW, I have that pluggable superspeed enclosure above and a Samsung Evo NVME stick, and the superspeed 10 enclosure is the bottleneck. I get 1 Gigabyte/sec in read and writes.
I used a cheap m.2->sata tray in my laptops second slot with the 128gb ssd and macrium reflect* to mirror the old boot disk to the new ssd.
Next up I'm going to get a 4tb data ssd to replace the 128, and swap out the laptops 60hz display for a 144hz display.
Unless the laptops your considering have soldered data drives, are under unusually stringent after care plans (enterprise), or you don't want to mess with hardware these are pretty straightforward tasks. You can probably Google (laptop model) ssd swap site:YouTube.com and watch some one go through the steps. If YouTube doesn't have anything replace YouTube with reddit.
My old eyes really appreciate the significantly sharper text. If you can't see things, well increase the font size!!
If I had a monitor that was twice the size (reasonable on a desktop), I'd be looking for 4K. Or potentially if I wanted 8 pt fonts to be shaped nicely... But of course, I couldn't read them anyway on my display... Anyway, on a mobile platform (what the original article is talking about), 4K is a bit of a loser unless you have super eyes, IMHO.
I should also say that I use Arch Linux with i3, powertop settings and set my backlight down to about 7% to get the longest battery settings. This is fine indoors, but if I'm working outdoors or in a sunny place, I'll have to up the backlight which will cut a couple of hours off the peak performance.
https://us.dynabook.com/computers/laptops/portege/X30/X30-F1...
It's ~1kg, but that's mostly due to additional RAM and the like.
[0] http://uk.dynabook.com/press/releases/dynabook-europe-porteg...
i have a 1tb one. it's pretty tiny. it cost me $70. why is it so hard to put one of these inside a laptop?