I may be talking nonsense here, since I'm not a developer, but maybe in general terms these projects can help for some code inspiration for your PDOS efforts with OS/2:
My 32-bit OS/2 work is nearly done. ie I support C90 and ANSI X3.64 sufficiently well to use native OS/2 tools under PDOS/386 to build a better version of OS/2 or anything else that someone may wish to do. I don't personally wish to write millions of lines of code to replicate OS/2 or Windows or whatever. I just want the basic functionality to exist. Perhaps different universities would like to build their own OS, and may choose to clone OS/2, and they can start from a public domain source base.
After some more technical cleanup of the 32-bit OS/2, I'm probably more interested in replicating (to the same limited extent) 16-bit OS/2, for PM32 with D-bit set to 16-bit, PM16 and RM16 - with a single NE binary app able to run on all 3 environments and without separate code paths. I have a Book 8088 to try it on.
BTW, I just checked, and PDOS/386 is about 330k (for everything required to bring up a prompt). ie it would fit on a 360k floppy.
I'm also interested in a public domain C compiler - which may involve bringing SubC up to C90 standard - or at least, close enough to compile the PDOS source. I don't currently have the skills to do that, so would need to learn that. That's the only thing still missing from the essential PDOS/386 suite - I use (a fork of) the copyrighted gcc 3.2.3 because we don't have a 32-bit public domain C compiler that can handle C90 syntax.
There is also an interesting "Sector C" C compiler which inspired me to write "Multi-sector C" using the same algorithm.
Or I may switch back to the mainframe, with z/PDOS.
A lot of the time direction is governed by others who are interested in public domain code and contributing something. So supporting others in their own goals is very productive.
Anyway, we'll see what happens. :-)