Freezing sweet breads

I don’t recommend it.

As your question suggests, yes, those little fissures created by the bumpy streusel create pockets for condensation and ice to form, which will make the topping soggy.

That said, I’ve been meaning to try this in the case where if I knew that I’d be heating up the baked dish in the oven, long enough to dry out and crisp up the topping. I imagine you won’t ever get it to maximum crispness however because I suspect it takes more than the 20 - 30 minutes at gentle heat to revive them.
Of course, you do a test drive.
Or, what I would do in this case would be to assemble both the wet and dry ingredients in advance, separately, refrigerating the wet ingredients, if it's only a matter of a few days, and prep the mini-loaf pans, and the streusel topping (refrigerating that, too), etc., and then bake them up within 24 hours of giving them.
Make sure you let them cool thoroughly before wrapping. Otherwise, the steam from the loaves will make the topping soggy.
As for the wrapping itself . . . I wrap tightly in plastic wrap and then wrap like a package with brown (organic "If You Care" brand) parchment, tied up with twine. Here's a recipe I posted, with a photo of some whiskey cake I bake in mini-loaves: https://food52.com/recipes/31846-kentucky-whiskey-cake-an-updated-version-for-making-mini-loaves

I use foil with the whiskey-soaked cheesecloth, but would not with a plain cake, though you could, if you wanted. I put those loaves in the paper mini-loaf pans to make them pretty. It's really not necessary. You can wrap in regular parchment paper, too, if you that's what you have. And you can tie the loaves up with whatever twine from the hardware store, or Christmas ribbon you have (or heavy woven, bound seam tape, if you sew and have some that would work!)
;o)