The Zoho One subscription (yes, it is a subscription, not a single product) does not cover all Zoho applications. Here is what we believe is a full list of what is not included in Zoho One as of today.
Additionally, it does not include: other applications from ManageEngine, Qntrl, TrainerCentral brands, and paid Zoho Marketplace extensions (the extensions can be bought separately and integrated with Zoho One applications).