I have built an ESP32-based display using a Waveshare 400x300 4.2 inch e-ink display. I simply hot-glued the display in place at the rear, and aligned the display until the glue set.

I made this holder for the display so that I could hot-glue magnets to the internal fin, and that allows it to stick on the side of my microwave.

The holder angles the display to make it more readable.

The version here has no holes but you could easily add them for buttons etc.