Can I use Paypal to pay bills in Taiwan?

What bills are you referring to? You cannot add PayPal account to Apple Wallet app. PayPal credit or debit cards may be added to Apple Wallet.

If the bills you’re referring to are apps, subscriptions and service from Apple, PayPal can be added to your Apple ID Account in some countries. You can see payment methods that are accepted in Apple ID Account in the support article I linked below.

Payment methods that you can use with your Apple ID - Apple Support

You’ll need to ask the PayPal support team. PayPal is not a product or service of Apple.

You’re welcome. I hope you have a great day!