Russia does not need allies to defeat the Ukrainian army. Given enough time they will win, even if sanctions/aid to Ukraine make it a pyhrric victory.
Part of the sluggishness has been the desire for the "targeted strike", something that appears to have been reversed with the less discriminate bombing of the last 24 hours.
How will the Russian army defend their supply lines after encircling a town? Ukrainians are armed to the teeth with handheld western weapons to destroy armed vehicles with, and Ukrainian infantry can just lay behind and wait. We are seeing Russian convoy after convoy be destroyed to surprise attacks. Ukrainians don't have to take the fight head on. They can just wait and take out the supply lines.
This is an unwinnable war for Russia, because Ukrainian infantry is armed and not willing to lay down their arms. Russia has learned nothing from e.g. Vietnam.
Russia is big country and it needs lots of men to defend it on all its borders, which means that the forces they can use for invasion are limited. RN it looks like that they run out of soldiers, and Ukraine already started counter attacks on some fronts, so I guess "they will win" will not happen any time soon.
With each day, Putin is scrambling to find all the help there is.
The only people fighting for him now are psychopaths and conscripts. The latter don't want to be there, and Russia is running out of the former.