Here is a forumosa thread that suggests it is easy to get household registration reactivated once you are back in Taiwan if you were born in Taiwan and had it before https://tw.forumosa.com/t/how-do-i-apply-for-passport-and-roc-id-details-inside/82074/3.
If you did not have household registration before (and your parent had an inactive household registration) when you were born, then you can find some discussions here Difficulties when applying for a TARC as NWOHR and Acquiring household registration as an NWOHR
If you have questions about whether you are a dual citizen, there is a good discussion here Does being a Taiwanese national (國民) make me a dual citizen?