This can't really be discussed without also clarifying how your target language and tools ecosystem does package management. i.e. are you expecting to generate

This can't really be discussed without also clarifying how your target language and tools ecosystem does package management. i.e. are you expecting to generate and version internal packages and then consume them from a feed? It seems like, if you don't have this facility then the monorepo becomes more compelling. Not to mention, are you building 1 or 2 apps, or a whole host of microservices. Without knowing that, your experience of mono vs. multi-repos won't be much use.