Technically 5 if you're using one of them for the headphone jack (which you wouldn't need if it was included on the device ready). Also the one with 4 already has a headphone jack included, so you'd still have 4 available ports.
And 3.
They're small and I could lose it and would have to spend even more money for a replacement.
Yet they don't sell in the USA, and they don't have a headphone jack. A company meant for repairability and reliability not having a headphone jack. That's like when framework removed it from the 16 inch laptop.
IMHO, you shouldn't use your phone number for 2FA anyways.