I haven't seen it, but there is a reality TV show about the ice road truckers on American TV.
In 1943 the Soviets closed in on Crimea and got to both the Kerch Strait and the northern border by November. They dug in for the winter and didn't continue to push into Crimea until April 1944.
Apparently the ground conditions were still good enough to move until well into November.
The climate is warmer overall, but there are still record cold winters too. Just scanning some statistics Berlin has had three years with snowfall levels in the top 10 in totals since 1886 in the last 20 years. 2007 was 118.5 inches, 2017 was 127.6 inches, and 2019 was 117.7 inches. I would expect the data to be in cm, but it is what it is
Most Yearly Snow in Berlin History
In a quick search I couldn't find similar data for Kyiv, but I did find this
Glavred: Kyiv sets 100-year March snow record - Mar. 24, 2013
That's from 2013.
When the Ukrainians get to the Russians the Russians are usually routed fairly easily. The biggest problem is getting through all the mines. If all the mines in the country spontaneously exploded tomorrow the offensive would go much faster.
Wars always end when one side becomes unable or unwilling to continue. The Ukrainians are chipping away at the Russians equipment and ammunition stockpile, but that is very slow going. Russian equipment losses to date would have crippled most armies by now, but they have had so much old Soviet equipment in storage that they are able to limp along with 1950s equipment.
Between the Russian ruling class being behind the war and the public being pretty much apathetic, Russian will to continue is not great, but it's still there. The public are against the war when push comes to shove, but they have been trained by Putin to be politically helpless so they just sort of ignore the war.
Ukraine is slowly waking the Russian public up to the pointlessness of continuing and they do that with Russian losses. The more Ukraine succeeds the more likely it is that Russia's public will reach the breaking point where they start to speak up about ending the war. If Russia truly loses the will to continue, then the war will be over. Putin will too most likely which is why he's also working hard to keep a lid on public unrest.
A major reason the west has been slow rolling supplies to Ukraine is most western governments fear what will happen if unrest breaks out in Russia. There are several scenarios that could lead to a very messy civil war in which there are nuclear weapons around everywhere.
Russia is using cheap, widely available parts for their weapons. I have seen no evidence that they are using anything which has a supply that can be easily controlled.
Even for Xilinx parts the secondary market is full of parts. I did a search on Ebay for Xilinx FPGAs and got over 1000 hits. Xilinx brand parts are surplus now that the parent company AMD has rebranded their parts. The mainstream supply chain for Xilinx parts is almost completely empty with AMD brand FPGAs replacing them.
I have thought one thing western intelligence services could do is identify a part that the Russians are using a lot of and make counterfeit parts marked as the parts the Russians want, then ensure they get into the Russian supply chain. All sorts of subtle things can be done to screw with weapons with counterfeit parts. Even if the Russians end up figuring out the ruse, they will have to spend a lot of time and effort screening for counterfeits and/or taking out the counterfeits and replacing them.