pcboot is a minimal 32 bit protected mode kernel, which can be used to make bootable PC demos or games. It's not designed as a regular standalone operating system kernel, and cannot be used as such. The intent is to link it with your codebase, or more likely build your demo/game code around the pcboot kernel code.
One of the core design principles is to allow starting pcboot programs from either traditional floppy disks, or USB sticks, and possibly CD-ROMs as well. The main idea is to make "down to the metal" PC hacking simpler, not requiring the maintainance of purpose-build retro-PCs. Nor having to deal with the inadequacies of MS-DOS, but rather follow a more Amiga-like approach of giving the finger to the ugly software stack of that time, and talk to the hardware, which is much more timeless and interesting, without middle-men.
A reasonable effort has been made to make porting DOS protected mode programs to run under pcboot, but don't expect that just re-building your existing code will work out of the box.
Copyright (C) 2018 John Tsiombikas email@example.com This program is free software. Feel free to use, modify, and/or redistribute it under the terms of the GNU General Public License version 3, or at your option, any later version published by the Free Software Foundation. See COPYING for details.
Yes, this means that if you release any programs which use pcboot, you will have to release the source code as well, under the same terms.
Let's drop any pretence that you have any good reason to keep your code to yourself. This is strictly a tool for retro-coding. There are no corporate secrets in a bootable PC demo. You can do it. If you insist on not sharing the code of whatever silly thing you make with the help of this, you can fuck right off.