I started building "real" firmware for my raspi appliances using buildroot. That makes it super easy to build images that completely run from initramfs without a single write on the sd card (and are fully booted in a few seconds including userland).

Only works if I don't need any local persistence but makes the Pi just work super reliably. Upgrading is as easy as swapping the Linux Kernel image on the fat32 and rebooting.