Not tax advice or any other kind of advice –
Check with IB. Ask them about the location of your account. Don’t open it if it is located in the USA and your primary purpose is to trade non-US stocks. Only do it if the account is domiciled in HK. Also, ask them about the brokerage and/or custodial fees that they charge for Taiwan trades and holdings (Schwabb has ensured zero brokerage commissions in US markets as the new normal, but I am very confident that it’s not zero for trading in Taiwan).
If your account is legally located in HK and you are a non-resident of Canada for tax purposes, you should be fine with CRA too. So you shouldn’t have to pay taxes outside of what you have to pay in Taiwan (see above comments – your Taiwan tax burden for stock holdings here is small and can be zero depending on what you own).
My main point is, don’t do it unless the location of your assets is in HK or more specifically any country that is not not not the USA. Non US persons who have financial assets that are legally located in the USA will be subject to US tax at some level. Non-US persons don’t have to pay capital gains but are subject to 30% taxation on US dividends, as mentioned above.
However, estate taxes on US-domiciled financial assets are insanely high for non-US persons. The US Federal Government will keep/take/disembowel your fresh corpse of 50% of your US-domiciled financial assets (of above I think $50K) when you join the choir invisible. I know, I know, it won’t matter to you because you’ll be dead and smoking dope with Janice and Jimmy and Lemmy… but it should matter to you while you’re alive.
So don’t do it, if your account is domiciled in the USA. That would be my advice (if not for the fact that this is not tax advice or any other kind of advice).
On the other hand, if you’re a resident of Taiwan, and you only really care about investing in Taiwan stocks, the very easy workaround to all of this would be to just open an account with a domestic broker in Taiwan.