I’m using EFISTUB instead of a boot loader (on the PC running Arch, anyway) and Windows hasn’t figured out how to break that, yet.
Somehow it hasn’t figured out how to ruin my systemd-boot bootloader on EFI, (NixOS, this time) either. Perhaps it just has better support for EFI than BIOS?
I tried to run some software on my router. It kind of works, if it fits. Storage was the limiting factor. There’s an option to expand the FS to include a USB stick, but somehow it made something overheat, and the router froze every now and then.