"Germanic" is a bit general, and pronounciations differ. The letter "u" is indeed "ooh" in German, but in Norwegian that sound is assigned to the letter "o", and the letter "u" (as in French) sounds like German "ü" (a sound that native English speakers are ridiculously bad at).

Also, Danish is just completely weird. I remember a Danish friend laughing at me once for pronouncing the Danish/Norwegian word "dag" (day) in Norwegian. There it's pronounced somewhat like the English "dug", but with a longer "ah" sound in the middle. In Danish it's pronounced like the English "day". WTF?

In short, there are no such general rules for "Germanic" languages, there are huge differences.