Seems like if the "boot.asm" (actually sector 0 of the floppy) could be made relocatable away from sector0, then it could still be functional when stored in a filesystem (including on a HDD) not unlike BOOTSECT.DOS. The remainder of the floppy (sectors 1 through 16 proper) when copied to the same sectors (which are normally blank and unused) on a MBR/BIOS style HDD work just the same as from floppy without having to be in a filesystem themself.

Then you could easily chainload to Floppy Bird on a HDD from other bootloaders (like WinNT5 & NT6), with no changes to the main ASM program.

EDIT: the comments in boot.asm refer to sectors 1 & 2 since they are the first 2 sectors of the floppy, these two are officially numbered 0 & 1 in a disk editor or DD command.