flo-rate wrote:

One answer could be to buy a known internal 2.5 inch drive whose spec you
like and mount it in an external USB enclosure.

At newegg.com, I can find a 3.5" 8 TB 7200 RPM drive at $440. For a
2.5" 7200 RPM laptop HDD, the biggest they carry is 2 TB costing $990.
With the 3.5" form factor, I get 4 times the capacity at less than half
the cost.

Yeah, 2.5" is technically doable but at a much greater cost per byte.
Of course, a 2.5" external HDD will probably fit [tightly] in your shirt
pocket (as long as there is no fan) but you'll need to tote the 3.5".
Who carries their 2.5" external HDD in their shirt pocket?