In my view, Russia got wayyy too cocky and truly believed their own bullshit about them being a superpower and being the 2nd most powerful military in the world. They looked down on Chinese technology and refused to embrace a full cooperation with China. You can see it in the how Russia has treated China, they are "allies", but extremely reluctant ones at best. If Russia was smart, they could have traded technology with China, especially a decade ago when they actually had stuff to trade with, or cooperated with more joint projects, or just bought more chinese weapon systems, either to use or to reverse engineer.
Just look at how Russia treated the AL-31s and S-400 purchases by China. They didn't want China to get the technology, so they delayed the purchases and fucked with it to get more money from China. If I was Russia, I would have given China the technology they needed in exchange for chinese technology where Russia was lacking in, like drones, avionics and electronic, or at the very least engaged China in more joint projects. Compare this to Russia/India joint weapon development, where Russia has a much more active role in helping India's development, to act as a counterweight to China, because again Russia thinks it's a superpower that can afford to sit on the fence and play two major powers against one another.
China's weapon development program has historically depended on Russia/soviet union. But that isn't shameful, you learn from the best, until you're good enough to innovate and develop even better weapons. That's how every major power in history has developed. China would probably be still be a decade behind Russia if it had tried weapon development without any help or guidance.
Honestly I think one of the biggest fuckups of the war was Russia's decision to always go full domestic and not buy any chinese military hardware before the war started. It's kinda insane to think that despite being allies and Russia deciding to invade the 2nd largest country in Europe on it's lonesome, Russia hasn't actually bought any chinese military hardware before, they do buy commercial stuff like a small amount DJI drones, radios or components like tires, electronics, bearings and raw materials but not ever a complete weapon system.
This will probably go down as one of the biggest fuckups of the last decade. Russia had a frontseat in the Azerbaijani/Armenian war where drones were playing a major role, they had an ally that has one of the best commercial drone companies in the market and plenty of military grade drones for sale and they didn't buy any for use, or to reverse engineer or try to rope China into a joint development program.
Russia must have known that they would get sanctioned after the invasion, that China wouldn't be able to ship them much weapons after the sanctions kicked in in fear of losing it's access to the Western market. That Ukraine was going to be very different from all of their previous invasions, considering it's one of the largest countries in Europe, or that America/NATO/Europe would be providing heavy support to Ukraine.
Chinese hardware generally outclassed Russian hardware, especially in areas like drones, electronics, radar, software and precision weapons, all important force multipliers. Even if chinese equipment were equal, or even inferior, having a massive stockpile when deciding to invade the 2nd largest country in Europe would have been a good idea, especially when you know that you're gonna to be sanctioned to death as soon as the war started. Not to mention that smuggling ammo and replacement parts is easier than smuggling in an entire artillery battery or tank division.
Of course, it won't help much now, even if China were to start shipping in large amounts of hardware today. But it would have helped greatly in the initial invasion, in their push to Kiev, if Russia had a few billion dollars worth of carefully selected chinese weapons designed to shore up their weakness in electronic warfare, drone/anti-drone warfare etc etc, things could have gone very differently. And smuggling ammo to an existing MRLS battery is a lot easier than smuggling in an MRLS battery.
It would greatly benefit China too, seeing as it would be a great opportunity to see how chinese hardware stacks up in an actual war and against NATO hardware and it they performed well, a great advisement for their performance to the world and the international arms market. If I were in charge of China, I would have offered Putin a big discount on weapon systems before the war started, granted that Russia provided China with all the raw data and an extensive report on how the hardware performed.
Instead we get this mess of a war where Putin is now asking Iran and north korea of all countries for weapons and ammo, because when you're desperate enough, anything goes. And chinese equipment, despite not even really being in the conflict, are also having their name dragged though the mud alongside with Russia, because the general public tends to lump the two countries military equipment/technology together espically with the long history of chinese/russian weapon development, where Russia has historically been the leader until the last 10 years or so. All because the Russian military industrial complex couldn't get their head out of their ass and see past their own propaganda.
I wonder if this war will finally get Russia to dig it's head out of it's ass.