100% agree, here's some more departments that you haven't listed but probably exist:

• Legal, internal contracts, contracts with suppliers, contracts with customers (advertisers), compliance with the laws of many countries/markets

• Regulatory, compliance with internal and external regulations

• Procurement, negotiating with suppliers

• sustainability, there's probably someone in the business reporting on gender balance and environmental impact and a host of other UN SDG considerations

• PMO, internal project management and portfolio reporting

• market X, there may be a team of people for each major market responsible for sales, infrastructure, compliance, etc. in that market, in addition to central

• CI/productivity, there will be some team responsible for reducing costs

• Product owners, there will be teams of people responsible for arguing about what features/bugs should be implemented/fixed

• monetization, there's probably dedicated teams looking at (and a/b testing!) new ways to push people into spending money on the app and/or interacting with ads more often