Weird Things to Consider
Power Supplies & Cables
The Pi 4 needs a healthy power supply. I've found that at minimum you will want one of those common 12W Apple USB chargers that are bundled with iPads. Most regular cell phone USB wall chargers will not keep the Pi running especially with a screen and accessories.
USB - C is a nightmare. One benefit of some USB C devices is that they can signal for varying charging voltages. This can be well beyond the standard 5V used in USB. Unfortunately if you have a USB C ON/OFF switch you may notice that it may not even work. If the power supply can't detect what it is supposed to supply some won't supply anything. So if you want to use one of those Amazon ON/OFF USB C switches you may want to just get a basic USB A "charger" (power supply), a USB A cord with C on the switch end.
The standard supported 7" touch screen works well with the Pi 4. WHAT ABOUT A KEYBOARD. On the roadmap the width and field name inputs will have a React based keyboard. In the mean time you can use the common matchbox on screen keyboard to type in the information. Once installed you can access from the
sudo apt install matchbox-keyboard
Pi Menu --> Accessories --> Keyboard
Also, if you get a touch screen with two extra signal wires (sometimes green/yellow) most likely you won't need those. The touch screen is supported over the display ribbon cable on newer Pis so you will only need the black and red power wires.