Hey,
In principle, it is possible to create a localization for a variant of a language. Here are all the necessary steps to include a new language to Common Voice: 📖 Readme: How to see my language on Common Voice
In my opinion, the hardest part for Moroccan Arabic will be to collect enough sentences. There is a Moroccan Arabian version of Wikipedia, but it only has around 4000 Articles: https://ary.wikipedia.org/
You can use the Sentence Extractor and it will give you a maximum of 12 000 sentences, and this could get you started. But if you really want to create a speech recognition, you will need hundreds of thousands of sentences. So this means a lot of manual work in the sentence collector.