Im so confused

I've tried absolutely everything. First I tried the guide, I messed up the guide so I did it again and it still didn't work, I tried a different version. Then I tried a premade efi, I tried a premade efi for an incredibly similar computer. I tried olaria, I tried combining olaria with my collection of efis, and at last I tried to use olcp to try and make an installer for an iMac 18,1 because it has a very similar CPU. I have absolutely no idea what's going wrong. The computer is an HP elitedesk 800 G3 mini with the 7500T. I have a 256gb data drive and a 128gb nvme for extra fast storage. Can anyone tell me what's going wrong? If you need more info just commend and I'll try my best to answer it