Sorry to disagree, but no, they are not dozens of different languages. The challenge with Arabic is that it has a rather large vocabulary, and different regions use slightly different vocabularies.

That being said, Darija, or rather North African Arabic is a messy mix of Arabic and Tamazight. Which can be difficult for Middle East Arabic speakers to understand.

For reference, I speak Darija and understand both classical and modern Arabic. It would take me a few days to adapt my speech to other regional variations of arabic.

What's your prior exposure to Classical and Standard Arabic ? The people I'm thinking about only have darija exposure without any formal education in Arabic and little exposure to pan-Arabic media.