How to cite a physical product?

In the example given, you are citing the specification, not the device. The same is true of the Ferrari. You are going to say something(s) about it, such as horsepower or wheelbase. So, find and cite the specification(s) needed.

Edit: For the TrueRNG, you cite the web page, if that's the best information available, using whatever your discipline's citation style requires for a web page. You're still citing the source of the information, not the physical object.

If you actually examine a physical product, e.g. reverse-engineer TrueRNG, then you describe the object you examined and the findings of your examination. So, "I disassembled TrueRNG model ABC, serial number XYZ, and measured the actual entropy generated by the frammistan module using Someone's Method and determined..." Similarly if you measure the acceleration of that Ferrari. (I don't think that's the question you're asking, but that's what the title implies.)

I'd take this in two steps:

1. Build up a table of random-number generators that you might cite or/and think would make for an interesting comparison.

2. Refer to specific random-number generators according to their entry in your table throughout the rest of the text (rather than by brand name, etc.).

1. The table of random-number generators

"Comparison of hardware random number generators", Wikipedia, is a good example. This table provides a wide variety of helpful information, from brand name and pricing to operating principles and technical specifications.

Each piece of information in the table is cited based on source, rather than citing the sources for each product together. For example, technical specs tend to come from more technical sources while pricing information tends to come from commercial fronts.

2. Referring to specific entries in the text

What would you type if you were going to add a reference for say the TrueRNG?

Personally I'd index the RNG's like figures or equations, e.g. "RNG (10)" instead of "TrueRNG". This can make it easier to concisely-and-unambiguously refer to the RNG's, plus it helps to avoid polluting the text with cheesy brand names.

I would think that citing "... of varying size and complexity" is different from citing "... of varying cost".

For the former, you are trying to reference physical properties of the product, so you want to cite a technical spec sheet. Here the relevant things to cite are the model number of the product and version of the spec sheet that you accessed.

For the latter, you are trying to reference the retail or market value of the product which varies between retailers and over time. Here the relevant things to cite are which retailer, the price they were offering, and the date they were offering it on.