Short of the spell that can toss most of reality's constraints
the game rules on their head, retrieving equipment merged into a druid's wildshape requires reverting the druid out of that wildshape.
When the equipment merges into the wildshape, it "become combined into one". There is no separating it from the shape as they are the same for the duration.
Luckily, this reality does not have to be for a sufficiently enterprising or reckless character as wish doesn't need to be bound by reality:
By simply speaking aloud, you can alter the very foundations of reality in accord with your desires.
So the reality of the equipment being merged into one with the druid in wildshape can be altered by using wish.
You might be able to achieve something beyond the scope of the above examples. State your wish to the GM as precisely as possible. The GM has great latitude in ruling what occurs in such an instance; the greater the wish, the greater the likelihood that something goes wrong.
One would expect expending a high level and rare resource to retrieve a less valuable item from the possession of another creature is unlikely to incur "something goes wrong", but caveat castor as there is a tradition of DMs twisting reality bending wishes.