they had next to no professional soldiers prior to their being invaded by Ruzzia
Incorrect.
After Russia invaded in 2014, Ukraine heavily invested in its military. NATO has also been helping them train for years now. Wall Street Journal
This is also why Russia faced far stiffer resistance in 2022 than they did in 2014.
two of their allied powers, Belarus and Chechnya
Belarus's involvement is very limited. They're mainly allowing the Russians to fire missiles from their territory. Wikipedia
Chechnya isn't a country or 'power'. It's the Russian equivalent of Alabama.
Wagner, chose to rebel over continuing to get fed to the meat grinder
It would be a mistake to think people like Prigozhin want to end the war. Russian ultra-nationalists want to intensify and escalate the war, not stop it.
Ruzzia is literally down to recruiting 16 and 60 yr olds right now.