The good thing with free software and free source code is that it is unlimited the possibilities and software range.
However most libraries that are public domain aren't efficient. Libraries use lot of processor,... and the whole system is slow.
Termcap is the king and build yourself you libs.
Compilers such as gcc,... are ok.
Well, graphics. gtk is okay, simple to use for everyone.
FreeBSD, Linux,... opensource Unix like, they look the same and they are very close.
NanoBSD is a good way to think.