You can get fairly cheap replacement parts on sites like temu.com or aliexpress.com; these will be made with LCD technology rather than OLED, with much less screen resolution but for your purposes that won't matter. AliExpress also has screens with defects that might also make a good choice for you. Here's a couple of examples.
[link|https://www.aliexpress.us/item/3256805839288276.html|iphone 13 pro screen replacement - Google Search]
[link|https://www.temu.com/incell-for-iphone-13-pro-lcd-screen-replacement-similar-size-notch-sensor-cable-lcd-display-touch--screen-assembly-a2638-a2483-a2636-a2639-a2640-with-repair-tools-g-601099800331127.html|incell 13 pro lcd screen replacement [similar size - Temu]
[link|https://elitecellparts.com/product/lcd-display-assembly-for-iphone-13-pro-ncc-advanced/|iPhone 13 Pro LCD Screen - ColorX - HD Incell]