Stuck at booting

Hi,

Late 2011 Intel iMac 27" here.

I tried installing windows using boot camp over the last days - created partition - used installer - tried booting Not very successful (see pic 4). - Uninstalled - wiped partition

Left the iMac powered (not eco friendly, I know!)

This morning, due to an electric shutdown, both my iMac (the one I tried windows and another very similar one running upgraded osx) were forced shut down (not clever, I know).

The windows tentative one didn't manage to start osx anymore.

Cleared NVRAm (see pic 3), heard the loud "tadaam!"

Still stuck (see bootloader pics 1 and 2).

I managed to boot recovery and am thinking to reinstall Sonoma...

Anything else I could try or is reinstalling my one and only option?