No. 1970 is 0 in Unix time. The NTP RFC specifies 1900. I had to look it up!
Better to represent it as a 64-bit unsigned fixed-point number, in seconds relative to 0000 UT on 1 January 1900. It’s how he would have wanted it.
In terms of language you are correct. But in terms of SI usage it seems to me OP is expressing it correctly. The SI unit prefixes have a name, a symbol and a multiplier. The prefix is a concept that encompasses all three of those attributes. So “kilo” is one way of identifying the 10^3 unit prefix, but the name kilo is not the prefix itself. It’s just the name we use to refer to it. And the symbol k in km is certainly the unit prefix portion of that unit of measure.
For flexibility and size I like external m.2 enclosures. I have some from Sabrent, Orico and Rosewill. Of them all the Rosewill is the smallest, has the nicest build quality, and seems to dissipate heat the best.
So I would recommend a Rosewill 9SIA072GJ92919, and add an NVMe SSD of your choice.
I think your MacBook is Thunderbolt 2, so you won’t get full speed but it should still be plenty fast. And this enclosure will give you TB3 speeds if you upgrade your PC later.