CloverBootloader VS OpenCore-Install-Guide

Definitely look into clover

You need to try and learn it ....clover is a bit eazy then OC https://github.com/CloverHackyColor/CloverBootloader/wiki/Configuration

I did manage to get Clover to boot, turns out it was a graphics card issue (Clover does not boot on ProLiant DL 560 Gen 8) so I threw an old HD 3470 I had laying around in it and I can now access Clover. I gonna play with Clover a little and see if I can get it to do what I want and if not, I grab the Slim ODD to SATA adapter you mentioned. Just need to find the cables to connect it.

In your case you may wish to research using a tool such as Clover Bootloader, which would allow you to install Proxmox to NVMe drives and then put Clover on an internal or external USB thumb drive. The boot process would start from Clover on USB before linking your NVMe installation and continuing from there.

Clover bootloader https://github.com/CloverHackyColor/CloverBootloader

You can use Clover to emulate UEFI on legacy BIOS computers.

Are there any other bootloaders I should be considering? My understanding was that LILO and BURG have essentially been abandoned so even if I were willing to rely on an abandoned project for something as important as the bootloader (I'm not btw) then it probably would not work with LUKS/Btrfs. While doing my initial research, I did come across Clover but I know even less about that than I do about Systemdboot and Refined. My initial impressions is that it seems very customizable theming-wise but it feels like maybe not too many people use it / I'd have a hard time finding help and that's IF it even supports LUKS/Btrfs.

You Clover outdated af (2017). Update to 5123.1, which is the last one with the old memory fixes: https://github.com/CloverHackyColor/CloverBootloader/releases/tag/5123.1

Check dortania’s open core guide

To keep costs down, Keep an eye on local market place and classified sites for a cheapish gaming PC with an AMD card in it (RX’s 5700 / 5700xt / 5600xt / 6600xt / 6600). Look up the parts here on Reddit and https://dortania.github.io/OpenCore-Install-Guide/ to see if people have problems or methods needed to make them work.

Idk much about amd gpu support but u can check it on Dortania’s open core guide which I highly recommend you to follow

Btw u can follow this https://dortania.github.io/OpenCore-Install-Guide/

I have similar setup (i7 8700K, 5700XT, Asus Prime Z370-a), everything works, no issues (wifi with OCLP patches). All you need is here: https://dortania.github.io/OpenCore-Install-Guide/

Go through the Dortania Guide.

I exclusively used OpenCore Dortanias Guide. I also useed OC 0.9.5