I just started the make deb portion, it's failing when it gets to the
FAILED: libcommon.a.p/hw_display_virtio-gpu-virgl.c.o . Applied the patch from pve-qemu/qemu directory with patch < virgl.patch
##edit
I started the process on another identical host, did NOT use bookworm-backports, used the deb-src for bookworm in sources.list, ran apt-get build-dep qemu virglrenderer. This installed almost everything. Builds fine after this.