Notice that the European model says that with an additional terminal strip, it is usable at 120v. But without that, it is 230v.

If you can get the terminal strip, then you can probably do it, but not without it.

I have used 240V light fittings fitted with a 12V LED globe in some garden lighting applications, running off a transformer.

So long as the wiring, +ve, -ve, and earth are properly connected, I don't see why you shouldn't.

I can’t comment on the compatibility of the light bulb nor the suitability of what you’re asking, but I can point out that the backplate of the U.S. version is a little over 4 inches wide and is made to mount onto a typical U.S. 4 inch electrical junction box which is embedded in the wall. The fixture’s backplate of the European version is substantially narrower so it wouldn’t fully cover a standard electrical box (and would mounting hardware line up?). The U.S. version is UL Listed to conform to U. S. safety standards and the European one is not. Notice that the U.S. version is for use with a T3 light bulb (which is 3/8” diameter) up to 200W (doesn’t sound like LED)…whereas the European one says it’s for the LED bulb (which is likely larger diameter - note the dimensions on your light bulb spec sheets. The maximum wattage ratings on the European one might be rated much lower than the U.S. version but not indicated on the European cut sheet. There are some potential issues with risk of fire, electrocution, and electrical code compliance that you [can] get further insight on. I’d recommend you contact Luce Plan tech support or a distributor to ask about your intentions to see if it’s suitable and what they recommend so you can make your decision. Also, I recommend you check with an electrician as well. I’m saying these because it’s along the lines of what my thought process would be if I were to have been asked a question like this when I owned a couple of lighting fixture manufactur[ing companies] a number of years back.

EDIT: two spots which I changed text slightly for clarity and enclosed new text in brackets.

You'll need to make a custom baseplate to adapt it to a standard American in wall electrical box. You'd also have to modify the bulb fixture to hold your desired bulb, but what I would recommend is adapting installing 12V led bulbs and using a transformer to power the fixtures with low voltage. That will drastically reduce the risk of messing up the modifications and burning down your house.

The Amazon USA compatible bulb I linked uses the same socket type and is the same length as the European light bulb.

I can put a low voltage LED bulb in any light socket I have in the USA without issue. would I really have an issue if I use the appropriate USA LED bulb for the Int’l model?

Wouldn’t I just need to modify the baseplate as the electrical wires between the models would not be different?

Thanks for all the detailed insight. I think the USA LED bulb looks to be the same lengthen and socket type as the Int’l version but the backing plate is certainly an item I would need to address in order to be in compliance and avoid fire risk. I am awaiting a response from the manufacturer and will contact an Electrian I know.

Yeah, I didn't notice that. If you're not modifying the socket and the US bulb fits it, this should work fairly easily. The wires might be different, but the international model is rated for a higher voltage. So you're fine from that regard. And at 20W, you're fine with whatever gauge wires they used. This should work.

Regarding fire risk, keep in mind if you or someone in the future installs the wrong light bulb in the fixture than what it is intended/labeled for (i.e. non LED instead of LED, or higher wattage than the fixture is rated for - even LED). Construction and labeling between these two fixtures are not the same, I suspect. Side note: even though LED is lower wattage it might get hot from a fixture testing standpoint so be sure to go with rated wattage per fixture manufacturer regardless.