How can I en- and decompress a bootable image?

I have a bootable kernel image, that I had created with MinGW Toolchain's that available for Microsoft Windows 11. The Project is in size tiny, but I would know: "How can I shrink the image, if it grow to pass it on a Floppy Disk." Thanks for Ideas. Edit: You can found a Example OS for this request at my git account: [**paule32**](https://github.com/paule32/JustFunOS_win32/releases/tag/Release)