Currently Russia is suffering a lack of manpower to keep its economy going.
Therefore, the paper figure of a 3:1 advantage maybe misleading."
I totally understand, and don't even know where their number of 69 million comes from -- compared to a total population of circa 145 million, how does 69 million compute?
And compared to Ukraine's number of 22 million -- out of what, are they still figuring circa 40 million as Ukraine's population?
So I don't think those numbers are particularly useful, except to illustrate Russia's potential advantage in manpower resources.
For actual numbers, each side has a whole long list of issues they have to work through in order to produce soldiers' boots on the ground -- at the front lines, with weapons, ammunition and other necessities.
PIF: "UKR, on the other hand, can rely on foreign assistance for much of the civilian production."
According to the usual sources, Russia's GDP is around 10 times larger than Ukraine's, so in theory, Russia should have no big problems outproducing the heck out of little Ukraine.
On the other hand, if you allow a vehicle engine analogy, a smaller engine can put out the same torque as larger engine, for a given speed, if you rev-up and gear-down the smaller one.
That's what Ukraine is doing.
Somewhere I saw an estimate that Ukraine is devoting something like 30% of its GDP to its military -- a number approaching the US in WWII -- while Russia is still devoting less than 10% of GDP to its military.
Of course, Russia's <10% is still much more than Ukraine's ~30%, but now we add in, mainly, NATO assistance to Ukraine and things start to balance out, somewhat.
For comparisons, notice US defense spending as a percentage of our GDP, with peaks during WWII, Korea, Vietnam, Reagan's Cold War buildup, and Bush's War on Terror.
Today's number is still less than 3.5% on this scale: