Yes, you can build one using Unity or other readily available solutions. If you have an existing website or online presence, an app builder like Magento App Builder can help you launch yours in an hour or two. Of course, with easy drag and drop.
However, the outcome depends on your requirements and budget. What features would you like to integrate into those 5 modules? The type of content, etc. Hence, I would recommend you to talk to an expert and go for a custom wedding planning app.