How to save Relational Data from Azure SQL Server (MS SQL) as a “Document Store” in Azure Cosmos DB for Mongo DB

I am creating an application and writing data to my centralized database i.e. Azure SQL Server (MS SQL). I want to save this relational data as a “Document Store” in Azure CosmosDB for MongoDB on hourly basis (so that I will read data from MongoDB) but I cannot find any suitable way to convert Relational data to Document Store data. I checked out Azure Data Factory as well but they have written that “When copying data to tabular source to hierarchical sink, writing to array inside object is not supported”.
Can you please guide me what approach would be best to save my relational data as a document store in Azure Cosmos DB for Mongo DB i.e. whether by Data Factory or Azure Function or any other way?
Note: My data would be very large