Inbound Taiwan customs for smartphones

Hello! I’ll be traveling to Taiwan in the near future from the USA (as a USA citizen). I was planning on bringing several new iPhones at the behest of some relatives for which they were going to reimburse me. I understand that travelers are required to declare anything in excess of 20000 NT$, which this certainly will be.

I was wondering if anybody knows how to figure out how much would be owed in duty tax on consumer electronics like smartphones? This information seems very opaque and hard to come by. I’ve seen some websites say that electronics do not incur a duty tax, but I haven’t been able to find such statements directly from a Taiwanese government page.

Additionally, would declaring these items put me on the hook to pay for my personal items as well (e.g. smartphone, laptop, camera)? It’s weird because normally these things would put me over 20000 NTD anyway, but I probably wouldn’t declare them since they’re personal items. However, declaring the phones would presumably flag me for more scrutiny.

I’ve also heard that foreigners are usually not scrutinized, but I don’t look like a foreigner as I’m Chinese-American. I’ve also heard that Taiwanese customs are pretty lax/forgiving. I guess the bottom line is I’m trying to gauge the financial and legal risks and seeing if anybody has had similar experiences. I’d like to do this favor for my relatives, but don’t want to pay a lot of money or get into trouble for something fairly frivolous.