Kernel Panic loop on iMac and no startup mode works

I would bring a second OS like recovery and erase it or bring this Mac in target disk mode to attempt a data transfer or erase/repair.

• https://support.apple.com/en-us/HT201314
• https://www.prosofteng.com/blog/using-target-disk-mode-to-recover-macintosh-hard-drive

It’s possible you have a hardware issue, but why not exhaust some extra steps before you attempt to erase the drive entirely and confirm it’s hardware or you just needed an erase?

When you follow the links above you can consider a data transfer and then do the erase. If no OS including internet recovery works, your kernel panics will be hardware to resolve and not software.

• https://support.apple.com/en-us/HT200553