Programs I write are generally designed not to depend on any particular internet services (if they need some, they are configurable), and this is part of the re

Programs I write are generally designed not to depend on any particular internet services (if they need some, they are configurable), and this is part of the reason to do. And, yes in the case of these FOSS it is probably easily enough to find an implementation and to work around the binary compatibility issues. In the case of a program written in an obscure proprietary dialect of Pascal that you do not have an implementation of, well, sometimes you might reimplement a subset which is enough to run these programs (I have done similar things in the past), although of course it is probably going to take longer and be more difficult than FOSS is going to be.