Not really, web pages (which do not depend on specific APIs) still work just fine, they just look antiquated.
Desktop apps in theory can run too, but it depends on what they link and if OS still provides it.
Desktop apps in theory can run too, but it depends on what they link and if OS still provides it.
It's not like any modern OS, or popular libraries/frameworks could not provide an equally stable (subset of an) API for apps, but sadly they don't.
[1]: I am young enough that when I last used DOS was before I had started programming, so I never learned it beyond command-line interaction.