I doubt its legal to do so, ITAR regulations come to mind first.

He's probably sipping a Busch or another brand that he doesn't realize is owned by the same company, because "gO wOkE gO bRoKe"

Ukraine has logistics for both NATO and Soviet ammunition. As long as the guns use either of of those it should be fine.

Ukraine has been using a patchwork of different weapons and calibers since the wars beginning. If we want to say all infantry weapons being sent are of the same caliber they have two old Soviet weapons and now NATO standard hardware. Grunts can carry a 7.62x39mm AK, a 5.56x45mm M4, or a 5.45x39mm AK. Ukrainian soldiers have been spotted carrying even older caliber weapons like the Mosin's 7.62x54mmR, 7.62x51mm NATO in FAL rifles, and I wouldn't be surprised if older equipment is in use. If this drags out long I'm guessing we will see the gradual standardization around 5.56 with NATO equipment as stores of Russian surplus runs out if it hasn't already and Ukraine is relying on captured ammunition for it's AK platform weapons.

On another note I am surprised the US hasn't supplied 5.56 chambered AK's, habits die hard in soldiers and I'm sure many would like to have an AK made reliably in the caliber being supplied.

The ones in the picture are likely a mix of 5.56 and 7.62 firearms. Both Ukraine would have in abundance

The rifles are mostly 5.56 or 7.62. The handguns are mostly 9mm.

Depends, looks like the rifles here are AK and AR style, so they probably take 7.62mm (which I imagine is pretty common in Eastern Europe) and 5.56/.223 (which the US military is probably supplying them by the bucket), respectively. That said, the hand guns are probably a mix of .22, 9mm, and .45 among other random less common calibers

These guns apparently came from a buyback program. https://www.nbcmiami.com/news/local/city-of-miami-to-send-guns-to-ukraine-city/2809291/

They take away from arrestees. Not just guns, but a butt load of personal property actually. It’s an income stream for most PDs.

Usually from people of color.

That's the point of the 2nd amendment. But technically civilians aren't allowed to own "military grade" weapons made after 1986.

But I live in a rural English town where the most exciting thing that happens is the elderly folk fighting over who has control over the flowers near the rectory. Are you saying they are russian agents? For real?

Edit: and now you've edited your post, making mine seem like nonsense.

The funny thing here is that Russian mobsters probably sold a few of those guns.

From what I can see, all in the picture are semi auto guns that can be bought at any Academy or almost any Bass Pro Shops in the US.