I’ve tried TXB0108 it does not work with Mega2560 serial.
Wrong tool for the job: Serial signals are not bidirectional; one has to be shifted down, the other up (and only if <3V). One direction per signal only.
Touch screen requires a lot of connections. And for those who loves resistors - yes it works with resistors,
but what is better 1 chip or 20 resistors?
20 resistors that do the job at hand is better than 1 chip that doesn’t. It depends on what exactly you want to do, which you STILL didn’t explain.
I thought a touch screen would need just 5 wires, not 20. 3x for the SPI and 2x SS to select display or touch panel. But if it’s SPI those MOSFET based level shifters won’t work… and anyway only the signals from Arduino to display need shifting (CLK, MOSI and the SS lines), the return signals (MISO) not.
If you want a suggestion that works for your special touch screen (20 signal wires?!) do post link to your specific display and let us know which exact interface you intend to use with it (had you done so in post #0 you’d probably have a complete working solution already…).