North Korea sided with the Soviet Union over China back in the day and people expect China to trust them? Kim purged his pro-China uncle and people expect China to trust him? North Korean historians continue to push their myth of Dangun Joseon while making historical claims on China’s Northeast, and this is supposed to be China’s ally? North Korea is a partner of necessity, not an actual ally.
And China 'allied' with the US against the USSR, how's their relationship today?
Look at where the US builds up strong allies. It’s not generally in its own side of the world. The US likes South American countries weak and corrupt; it prefers countries next to China and Russia strong and capable. It should be obvious why that is.
Strong allies? Countries in EU such as Germany or France? Well, they are developed economies (currently with quite the problems, and the US is basically leeching off them lol), but in terms of military power, they really aren't a threat at all to China, and that's with the unrealistic assumption that they could move their whole military to fight against the PLA (not to mention they likely don't want to do it lol).
SK and Japan? Again, yes they are developed economies (well China is basically eating into their industries lol), and militarily? Really not a serious threat to the PLA alone, they can be a supportive element in a China vs US conflict so there is that. But we all know, that more than allies, they are direct vassals with US military on their land.
If China is to cultivate strong allies, best do it near Western Europe and America. Not next to itself.
Allies isn't that easily cultivated lol, not to mention who? Canada and Mexico? It's one thing to have trade and stuff like that, but becoming allies and potentially risk being attacked by the US? Lmao.
As for in western EU, again who? UK? Scotland? France? We all know they aren't gonna be 'real' allies, at best improving relations and trade so they might stay more neutral in an event of conflict with US.
All in all, current stance of China is not to do stuff like NATO and 'allies' like the way US do it, but rather trade and diplomacy while most importantly improving itself, herein the PLA.