In the end I brought $20000, because I had to taxi from Taoyuan instead of KHH (long story) and have to pay for a COVID test at the end of quarantine. The hotel wanted cash for the food part of my stay, which was unexpected so good thing I had extra.
For my case, if I could go back in time I’d advise myself to bring $30000 NTD so I don’t have to look for an ATM as soon as I’m out of quarantine.