The solution with Russia is just to delay them and snag them up until they end up in a war with China.
China is expansionist, genocidal, and looking to "make China great again". Eventually XI will move militarily.
The resource rich Siberia is just north of China's land border. China needs oil, gas, timber, minerals, and it is all sitting right there. The current border was created in 1860, during the time known in China as "hundred years of national humiliation". To make China great again, that humiliation will need to be addressed. Be it in Taiwan, or in Siberia. Or both.
Russia's own technique of moving its citizens into Ukraine, and then moving in militarily once the demographics have changed is also reflected in Chinese migration to Siberia. What we see playing out between Russia and Ukraine is playing out between China and Russia, with the roles flipped.
In time Russia will have to turn and fight China. As long as Russia is not allowed to establish in Ukraine in the mean time, Russia will pull out on its own. It will then turn into fighting the Chinese to the last Russian, in the same manner the Chinese are fighting India to the last Pakistani. A bloody generational affair that will keep China from ever realizing its Chinese century or becoming great again...