DietPi is a highly optimised & minimal Debian-based Linux distribution. DietPi is extremely lightweight at its core, and also extremely easy to install and use.
https://dietpi.com/
1dc12a66809b14650d81f2eefba6b5092f60d67e50aab688dc1f669a4c8e326d DietPi_NativePC-BIOS-x86_64-Trixie_Installer.iso
This version is for BIOS/CSM.