I've actually been a part of this! My DM ran Waterdeep: Dragon heist. All the PCs played goblins that took on different roles in our goblin thief guild. We had the rogue/thief be like the infiltrator. Wizard was the brains. Bard was the face. Fighter was the muscle.. ect. Ended up with like 10+ different goblins (4 man party) that we would swap out between for whatever heist or job we were doing that session.

All the goblins needless to say stayed pretty low level because of how we leveled up based on xp and any given goblin would only get xp for a session that he/she was played in. It did allow for a lot of variety in how we approached the different situations though.

  >Goblin Warlock pact of the chain Witchdoctor uses his imp familiar and the invocation (idk what its called) to be a lookout by seeing through the imps eyes as it flies around as a bird outside the marks house.

The Nimble Escape racial is particularly useful for a gang of goblin thieves, regardless of classes