It's the wifi library that takes up a lot of memory, I'm using BLE and as a screen an old android phone (just as long as it has BLE) and you will save a lot of pins and power for the touch screen, in addition to the fact that it will be wired with ESP32, while if you use a phone you can make different Apps each for an Esp32 board with its sketch and peripherals.
Unfortunately adding ram on ESP is not as painless as adding it on a PC, you run into limitations.
Not if you saw my post where I use ESP32 and BLE ... I'll give you the link