The omicrons are pronounced like the short “o” in English (“offer”).
If they were long “o” omegas (“open”), you would be correct.
The upsilon is pronounced like the “oo” in “book,” or French “eu” in “bleu.” (kind of like a schwa, although it’s an accented stressed syllable in “οὐρανός”).
FWIW, that’s what I was taught when I learned Koine Greek.
I’m just waiting to see how long it takes for the first person to make a joke about long O’s.
