Am I missing something? The submission under which you posted this comment literally solves the problem you're complaining about, and directly contradicts the claim "you still have to be on Apple" for this experience.
That's a feature, not a bug. Why should I have to be locked in to a proprietary file sharing mechanism that my device manufacturer unilaterally declares I must use?
To have 37 different implementations to achieve this, might be a feature. To have 37 different protocols surely is not.
There should preferably be one open protocol for proximity based wireless ad-hoc file sharing. This protocol can then be implemented by operating systems and/or userland implementations