You could do the whole Lightning PoS + NFC with a cheap Android phone with NFC support. Here's one for $120.

If you want to add more cool stuff, check out the magtag from adafruit. It has the ESP32-S2 and a small grayscale E-Ink display. It also comes with buttons, four RGB leds, a small speaker, a light sensor, triple-axis accelerometer, and more stuff. And the cool thing about it is that the screen remains on even if there's no power!. You only need power to change what's displayed. It's easily programmable through USB with any computer.