None of those nations will sell any weapons to Taiwan, period.
Money talks
None of those nations will sell any weapons to Taiwan, period.
Money talks
As I suggested before, Japan may sell her few surplus subs to ROC once new units are comissioned, at least as a stop gap solution.
As for nukes, Japan has the biggest plutonium stockpile and can build a nuclear weapon in about a year-and than extend the proverbial "nuclear umbrella" over its former colony. I also read that ROC been shipping uranuim from S.Africa. But all this may not be as important: even if Taiwan gets them, they'll be used as a detterant, and if that fails, as a 2nd/decapitation strike against the agressor/unifier-whichever name you preferr. China will not tolerate Korean unification under ROK leadership, and US and/or Japan likewise will not tolerate Taiwan's re-unification with PRC under current Chinese leadership. ROC will invest in conventional precision missiles of all types, and meanwhile Taipei knows that S.Korea, Japan an US will come to its aid if for nothing else, to protect the SLOCs Taiwan's strategic location is in the position to control. Enough said!