Most of high resolution LCD displays for Raspberry Pi use HDMI connection and implement HDMI to LVDS or HDMI to MIPI DSI converter circuit. Newest Raspberry Pi CM4 exposes 4 lane MIPI DSI connector, allowing to directly connect LCD panels for mobile applications.
One of these panels is JDI LT070ME05000 - 7" 1200x1920 IPS MIPI DSI panel, used in Google/Nexus 7 tablet 2013 edition. It's 8 years old panel, but still looking good for DIY projects in 2021 and available starting at ~$20. Driver for this panel is a part of Linux for years and run successfully at Raspberry Pi CM3. It wasn't popular that days, since CMIO board for Raspberry Pi CM/CM3 was good enough for developers, but definitely missing features and connectivity that makers expect to see out-of-the-box.
Long story short - only simple adapter board needed to make this panel work with CM4 CMIO board and sources/instructions are published in our GitHub page
We also encourage CM4 baseboard developers to use Raspberry Pi 22 pin DSI connector to make more DSI panels available, just like we did in our CM4Ext Nano, worlds smallest CM4 baseboard