Yes absolutely! I used my phone to purchase almost everything on my last four trips. Be sure to tell the cast members that you're "paying by phone" so they can hit the right button for credit/debit cards. Then the Mickey logo will be ready to accept your payment.
If you just put your phone to the Mickey without telling the cashier, it will be looking for a MagicBand, and it won't work. The problem at the beginning (around 2 years ago) was that CMs weren't educated on how the NFC system worked. About half the time, I let them know what to do and they ended up very excited, telling the cashier next to them, "Wow, check this out... did you know that we can take Apple Pay?"