Compare to the basic Nextion 3.5, Nextion enhanced 3.5 add new functions: support built-in RTC, save data to Flash, GPIO, larger flash capacity and faster CPU.
There is bug in Nextion HMI file. If you power it with micro USB interface, nextion display may wrongly show T series. Please power it with CR1220 battery and connect 4 pin cable, then nextion screen will show K series correctly
Its easy to adapt Nextion family HMI to existing projects, you just need to provide it a UART.
This is nextion 3.5 case, only for enhanced not basic, https://www.amazon.com/dp/B079161H78
You can buy most nextion display here, https://www.amazon.com/nextion