It is not allowed if you are over 12 years old.
If my father has money, he can get investment immigration (about 4 million yuan). However, even if he becomes a Taiwanese citizen, the issue of military service is very troublesome. He has to serve as a soldier for two years. I can't guarantee whether anyone will bully him during these two years of military service because of his special status.
I went to Taiwan because my education was different (mainland academic qualifications are not currently recognized). Unless you are very good and the Fortune 500 or high-tech companies based in Taiwan are willing to hire you, you can only do bricks and mortar work. Jobs such as waiters and processing plants that do not require academic qualifications. (If you have the ability to become an investment immigrant, it doesn’t matter if you have the money to open your own store)
Since you have decided in the past that your children will be educated here and become Chinese nationals, don’t change it again and again, and stay in the mainland with peace of mind. Development is also his destiny. . . .