Talked to another Chinese PhD student the other day. He said if Taiwan were to use its hypothetical nukes against China, blow up the Three Gorges Dam, or taking other military actions that cause millions of civilian deaths on the Mainland, the words "liberation" and "unification" would simply become "extermination."
Which is one reason out of many why Taiwan would not consider developing nukes. If China has threatened or ever threatens Taiwan with nukes, then I can understand but escalating from a much, much, much weaker position is hilarious a suggestion by whoever wants to make the claim.
Mainland invasion of Taiwan island without US assistance will almost certainly be successful. So it is up to Taiwanese leadership to decide whether a successful mainland invasion is going to end with Taiwan throwing some nukes at China (I doubt China will respond with nukes here*) and then having all the Taiwanese decision makers held accountable (certain death) and hopefully all those nukes intercepted OR go through with militarily forced reunification where most of Taiwan will remain intact and both sides suffer minimal losses in equipment, infrastructure, and lives.
Even if we assume American actors/directors and stooges within Taiwanese decision makers use the nuclear threat to hold mainland against invading Taiwan, the Taiwanese leadership has enough say and skin in the game to understand this is way too risky a move and will end with them punished and dead one way or any other way. It's just a matter of how destroyed do you want the island to end up as. Neither China side wants it destroyed! That's for sure otherwise mainland invasion would have happened (could still potentially if diplomatic means are totally exhausted and escalations happen).
* Mainland won't nuke Taiwan back if it gets nuked by Taiwan. It'll far more likely retaliate against the US if mainland gets devastated beyond a certain "acceptable" limit wherever that limit might be. Because the mainland would correctly understand any Taiwanese nukes would only exist and launched at the insistence of the US and stooges. On top of this it also makes no sense to nuke yourself because if Taiwanese nukes are flying, PLA has invaded Taiwan and it will be successful so since you already more or less own the island, why destroy everything on it that's worth a damn and make it unhabitable??! So surely CCP isn't stupid enough to blunder that way. It'll literally be PRC nuking what is essentially PRC at that point. What they'd want to do is nuke the actual instigators - USA, and kill the Taiwanese decision makers that have made such an outcome possible. This discourages those actions as already touched upon above.