Thank you for the donation.

My idea: Debian Bookworm real 32bit system without GUI and then install Retropie?

Not quite - use Debian with a minimal GUI (XFCE/LXDE) and a 64 bit system. On a PC, RetroPie is meant to be used from a desktop session (X11/Wayland). Next week the new Debian Trixie (stable) version will be released and there will be no more 32bit installation images (just like Ubuntu/Fedora/other distros), so use the 64 bit installation image.