Hi,
Just as an example, the Zettle shop (https://shop.zettle.com/gb/till-systems) shows an Epson printer (appears to be similar to one of the models at https://epson.com/mobilink-mobile-pos).
However, AirPrint is not mentioned for these Epson models, but iOS is. The TM-P printers are not listed in About AirPrint - Apple Support.
Generally speaking, for iOS compatibility with a non-AirPrint printer, additional software (for Wi-Fi or Bluetooth) from the printer manufacturer would be required.
There may be other suitable printers that use AirPrint. See the above Apple article, or try a web search.
I suggest that you contact Zettle and/or Epson (or another printer manufacturer) for details about what you need for your intended setup.