Old distro version on new hardware

I am trying to install CentOS 6 on new hardware for testing because our software is dependent on the package versions in CentOS 6. The trivial answer would be to update the software to run on a newer version since CentOS 6 is well past EOL, but I'm not a software dev and we will be looking at the LOE soon. The current state: - The machine has an Intel 13th gen i5-1335U processor with a UEFI only BIOS (no legacy mode) and secure boot disabled - CentOS 7.5+ and Debian 10.0+ works, but earlier versions do not - I am using x86_64 installers and burning them to removable media with Rufus in UEFI mode - I have verified that when installing they are using GPT partitions - The installers themselves will boot into GRUB (legacy or 2), but when it tries to load the kernel and initrd/initramfs it fails - Currently I have Debian 12 installed with CentOS 6 so Debian is controlling Grub 2, but it still won't boot into CentOS 6 -Older hardware which have legacy mode in their BIOS is able to use both MBR & GPT partitions and boot CentOS 6 (Intel Atom E3845) - I am able to virtulize RHEL 6 in Qemu running in Debian 12 Failed attempts to fix so far: - Recreated the RHEL 6 initramfs in Debian 12 - Modify the RHEL 6 GRUB 2 entry - Use the GRUB 2 OS prober to create a RHEL 6 entry - When loading an installer it either goes to a blinking cursor or the GRUB splash image is frozen on screen. In that state I am not able to switch to any TTYs - Adding echo statements to a custom GRUB entry makes it seem that it loads the initramfs. It shows the echo statements before loading the kernel, after loading the kernel but before loading initramfs, and after loading initramfs. After the echo statements show on screen it either reboots the machine or hangs with no TTYs. My current theories: - The kernels are not compiled with necessary modules/parameters - There is something with initrd/iniramfs which is preventing the kernel from booting - The intel microcode included with the installers does not support the newer processor - Even though secure boot has been disabled I need to install a self-signed MOK & shim Any ideas on why an older distro won't load on new hardware?