Canada

So, take some of these figures with a grain of salt. 6% for modern Russia sounds right, and >25% for the Nazis and Soviets during the second half of the 20th century sounds right. North Korea and maybe Eritrea would be the contemporary examples of that, although it's hard to collect the data. However, the Saudi military is famously useless (on purpose so there's no coups), and I imagine the money given out is mostly a slush fund for the appointees that run it.

However, there’s a caveat-- at some point, Ukraine will run out of soldiers to operate the equipment. Then what?

Indeed. Aside from internal trouble in NATO-land that's Russia's main path to victory. Ukraine is pretty populous itself, so it's not hopeless, but we can't rule it out in the long term either. But, I'm not sure unilaterally getting involved is a good solution.

For one thing, we'd lose our article 5 protections (otherwise NATO would get drawn into everybody's pet projects) and would run the risk of a direct Russian invasion. I don't think they could do it, because the oceans and ice cap are a pretty tricky obstacle, but they would definitely bomb us and our little airforce couldn't really stop them. That's a big sacrifice.

Internationally, that would piss our friends of the to Nth degree. It would be a hell of an escalation in a world that's worried about MAD, and the bombing raids on Calgary would be right across the 49th from America's missile silos, which would make them very nervous from a first strike perspective. From a propaganda perspective this would also look great for Putin, as suddenly he's directly fighting the West, and someone from the West he might beat sometimes. Put together, I fully expect Canada would get kicked out of all the clubs we can be kicked out of, not that you really need CETA that bad with ports that aren't safe for civilian traffic.

My main hope for Ukraine going forwards is new technology. Particularly, Sweden's Gripens were built with this exact war in mind, just further north, so Turkey needs to get out of the way. Other than that we just have to hope they can kill 4 Russians for every Ukrainian, or that Putin's hold on the domestic situation is indeed tenuous.