Is Milo's belt warded against the usual effects of trying to have a bag of holding or portable hole interact or has he already come to terms with the safety of wanded magic's extradimensional spaces and his brand of nondimensional space?

I don’t think HP-magic extradimensional space would trigger the bag of holding/portable hole implosion.There’s pretty specific wording about those two magic items that doesn’t seem like it would apply to the more vague effects of wanded magic.