I've always heard the acronyms I listed as "yoo-nih-sef", "po-tuss", and "oash-a" (the first syllable like "ocean"). It would be genuinely surprising to me to find out that those were not the standard pronunciations, but I guess it's possible that I've been living in a bubble my whole life!
From the limited Spanish experience I have (a few years in middle school and high school), I was aware of the subtleties of how "g" is pronounced with relation to the following vowel, but I didn't know about how "GIF" was pronounced! It fits what I remember about loan words though; I think we had the word "hockey" as a vocab word once during a unit where we had all sports words, and we were taught that it was pronounced the same way as in English, which stuck out to me given that "ho" at the beginning of a word in Spanish would usually not have an "h" sound like in English. Of course, "ck" is basically never found in real Spanish words either; from what I recall, "k" isn't really used much at all besides in loan words!