You are definitely on to something in how some communist states were partially motivated by not wanting to have a mirror image non-communist alternative, however in allusion to VTGothic’s point about framing and perspectives, I think a lot of discussion about forms of government and semiconductor microchips and economics misses a very core issue that is at the heart of this dispute (China vs Taiwan, or more properly the People’s Republic of China vs the Republic of China) and which is (or was) ultimately at the heart of tensions, disputes or wars involving the other communist/non-communist dynamics at play with West vs. East Germany, North vs South Korea and North vs South Vietnam (and the lesser known North vs South Yemen): simple nationhood.
Step back for a moment if you will and consider this question/scenario - would you as an American/Australian/Canadian be okay if the South/Western Australia/Alberta had split off? Never mind the high minded ideals about self determination, how would you feel in your gut if that happened? If not, then why would any leader of China/Germany/Korea/Vietnam be okay with a portion of their country being set up as a separate country under a rival government (whether viewed from the communist or non-communist lens)?
Because ultimately even in the West Germany vs East Germany dynamic, East Germany only ever initially claimed to be the legitimate government for all of Germany (i.e. Lesser Germany or East + West Germany) and had no problem recognizing the government of Austria even though Austria is and was for all intents and purposes a nation of German speakers living under a non-communist government which could have embarrassed the East German government if it did better for its citizens than the E. German government did for theirs. Even if the East German government was sympathetic to the Austrian communists, it wasn’t promoting the idea of a communist Austria being a part of (a fully communist) Germany.
With simple national sentiment being at the core of these issues, then for pretty much any communist leader of China, the very prospect of Taiwan potentially declaring itself independent from China (and tossing the Republic of China/ROC name for itself into the dustbin) and such a declaration being recognized would be viewed as an existential threat. The West has not helped to assuage such suspicions given what happened with Kosovo where most Western governments simply recognized Kosovo’s unilateral declaration of independence despite their operating in Kosovo under a UN resolution (#1244) which included provisions respecting the territorial integrity of FR Yugoslavia (with a few even unashamedly resorting to the flimsy excuse that the resolution applied to Yugoslavia and not Serbia despite the fact that Serbia is the successor to Yugoslavia and will indeed even be saddled with paying off even communist Yugoslavia’s debts until 2041 apparently - so clearly there were double standards at play).
These double standards are even more readily apparent when one contrasts how the West treated a defeated enemy (Yugoslavia) versus one of their own (the UK). Consider the contrast in approaches to Kosovo versus Northern Ireland. In the former the controlling state is forced out and then the provincial authorities are supported in their independence declaration whereas in the latter, despite a massive Irish lobby and sentiment within the US, the American approach was one of supporting a peace process that guaranteed UK territorial integrity whilst allowing the locals of Northern Ireland the freedom to choose their own identity and a guarantee on a referendum on reunification with the rest of Ireland at some point if that’s what they want.
If you were a Chinese leader and watched all of this (in addition to seeing your embassy bombed in Belgrade while Western governments were busy forcing the Serbs/Yugoslavs out of Kosovo) would you genuinely believe the assurances of American and other Western politicians that they support the One China principle but are opposed to the use of force to reunify Taiwan and China? Or would you rather suspect that they don’t support the One China principle they agreed with you previously whilst being truthful in opposing the use of force to reunify Taiwan with China.
All the various reasons usually given for China wishing to reunify with Taiwan (microchips, control of various waterways/access points/straits, not wishing to see a rival form of government, economic reasons) are, I believe, ultimately secondary and their prominence blinds us to the REAL dangers that may lie ahead because the basic truth is that all Chinese leaders are likely to view it as non-negotiable that Taiwan is a part of China and its people are a part of the Chinese nation. This truth means that pretty much any Chinese leader WILL fight to keep Taiwan from trying to formally separate and foreswear reunification forever, just as how the US government did fight to keep the Southern states in the Union and likely would fight again if the prospect of secession was on the cards (and it wasn’t an area that the US government actually would want to see leave the Union for some reason). I have very little doubt that any US government of whatever ideological flavour or stripe (be it democratic, or absolute monarchist, or liberal, or communist) would fight the prospect of a state seceding. We don’t even need to stretch our imagination that much as certain Americans of a certain political persuasion are already being demonized/characterized as enemies and have been told in no uncertain terms that if they wish to fight against the US government then they need to packing F-15s rather than AR-15s:
Right now, you can’t go on and buy an automatic weapon. You can’t go out and buy a cannon. And for those brave, right-wing Americans who say it’s all about keeping America, keeping America independent and safe. If you want to fight against a country you need an F-15, something a little bit more than a gun. — President Joe Biden (2022)
And this only 4 years after a Representative from the same party mused that a new civil war in the US would be short because the US government had control of nuclear weapons:
And it would be a short war my friend. The government has nukes. Too many of them. But they’re legit. I’m sure if we talked we could find common ground to protect our families and communities. — Rep. Eric Swalwell (2018; Twitter)
Those are not the statements of persons who would be okay if one set of Americans who see things differently wished to separate and take their lands (on which they might form a majority who hold such views) with them. You don’t allude to using F-15s and nukes against persons who you would be okay letting go (with the clump of sod they happen to live on).