What's funny is that the ROC actually claims more land than the PRC.
The funnier thing is that the ROC is essentially forced to continue claiming those lands lest it do anything constituted as a declaration of independence.
But I don't think the PRC claims any of Mongolia, Russia, Pakistan, Bhutan, or Myanmar, so I doubt they'd care if the ROC gave up those claims.
Another funny thing is that Taiwan claims all of Mongolia, and they are 2 of the 5 or so freest countries in Asia according to Freedom House.