Hey all!
Not sure if this was ever mentioned here but we have a useful best practices guide for the Veeam Public Cloud products as well.
There you should be able to find information such as recommended number of instances to be protected by a single policy, number of minimum workers depending on your workload, recommended instance type/size for the appliance and workers based on your workload.
In case you are wondering how to plan your deployment this is a good resource to check and might be helpful to you.