using and securing Sharding data

Question

According to the description from Azure here, you use Sharding when you want to split large databases into smaller components.

We want to use Sharding data, not because we have large amount of data, but because we have almost same schema from different organizations.

I need some advice and opinions about having multi-tenancy architecture and sharding databases for organization-related data. Is Sharding a suitable solution? How should you secure data that the users from organizations should have access to their own organization data only.