At the point of them taking in input to process, audio that comes from a microphone or comes from a file is basically just a series of numbers and is the same. So there's no barrier in terms of feasibility.

Whether they're all set up to do that "off the shelf" is a different matter but it should be fairly straightforward to add this to any that lack it and because they're open-source anyone could do a bit of Googling etc and find suitable code to adapt to do it. I know DeepSpeech definitely can take audio from files directly as input as I've used it that way before, and I strongly expect many (or possibly all) of the others could too.

DeepSpeech and Vosk can accept audio files, although each wants them formatted in a slightly different mono WAV format.

See my other comment for a comparison of the two: https://news.ycombinator.com/item?id=24248238