Rather than arguing about what is and isn't a zip code, here's an actual answer: no, at least on Firefox Android (and I assume generally on Android devices), if you have "inputmode=numeric", then the only keyboard available to the user is the phonepad-style number keyboard, and they cannot switch to another keyboard.
This honestly surprised me, my expectation was that it would select a keyboard by default, but you'd still be able to switch to other keyboards manually. So I guess if your zip/postcode/PLZ/etc field needs to accept international values, don't use inputmode=numeric (or similar) on it.
For a document that purports to provide clarity they're sure playing fast and loose with terminology. The first one on the list should be "all postal codes are ZIP codes" because that's false but but evidently programmers believe it.
Mine's an 'eircode', but there's no eircode field on Amazon deliveries, and we're told to use it as a zip code. Naming aside, companies that don't let me use "D02 R9D3" [sic] as a 'zip code', and mandate zip codes and/or lack a freeform field to put it in, can't deliver to me.
I'm of the mind that you can't just casually cast naming or precision aside when talking about data collection.
If I'm askimg for a ZIP code I probably already know I can't deliver to you. If I thought I could deliver to you I'd collect the data necessary to do so, though not by asking you to pretend that the meaningful differences are not meaningful.
Others operate differently, Amazon makes a bunch more revenue than me, YMMV.
Canadians have long dealt with this: credit card companies have a fun hack where your postal code has 3 numbers and 3 letters; drop the letters and add 2 zeros. So v4r 2x3 becomes 42300. Since this is used as one component in identity verification, the lossy correspondence is apparently considered good enough.
They're referring to the use of the trailing slash in examples like this:
<input type="text" inputmode="numeric" />
Such slashes were mandatory in XHTML for such elements but aren't a thing in HTML. They're also not invalid, the HTML validator says "Info: Trailing slash on void elements has no effect and interacts badly with unquoted attribute values."
