Since the need for this has to do with a read-only nfsroot with a systemd.overlayfs, I created a nofbturbo.service which executes a bash script that greps /proc/cmdline for a nofbturbo kernel command line parameter. If nofbturbo is present, it “deletes” the 99-fbturbo.conf file from the overlayfs. Now all nfsroot clients use the same image, and the tftp boot config files alone, dictates the rendering. So some clients are hardware and some software… pretty spiffy if I may say so myself.