A project appeared on Kickstarter Compute Blade. These are small plug-in servers with Raspberry Pi Compute Module 4 that you can plug into a box and then place it in a regular server cabinet. 4-module, 10-module (10-inch wide) and 20-module (standard 1U 19-inch) boxes are available.
Each blade has one Raspberry Pi Compute Module 4, NVMe SSD up to 22110 (2230, 2242, 2260 and 2280 are supported), gigabit ethernet, power supply via PoE, special passive cooler and one fan for every two modules. 548 thousand dollars have already been collected on Kickstarter, which exceeded the target amount. You can support the project on Kickstarter for 59 more days.