Using multiple datasets in Sanity for managing multiple Shopify instances

Is there a way to add datasets as an add on instead of changing plans?

Until someone gives you an official response, I can tell you that I asked a few months back and at the time the answer was no. That said, while each project gets a certain number, you should be able to freely spin up more projects. (Might be helpful if you wanted them for testing, for example)

You will need to upgrade to add datasets within a single project. Scroll down here for the details on datasets included.
But you can also
export and import data between multiple projects on any plan. Simeon’s duplicator tool is quite nice as well.

If you choose to create a new org and upgrade, you should be able to easily move existing projects into the new org. (it can be a bit confusing exactly how projects exist on their own outside of orgs and admins)
After creating an org, go to Settings > Transfer Ownership. You should get a prompt with a list of orgs your account manages. Once the project is in an org go to the Plan tab to upgrade if you want. And project plans should be downgrade-able later if you no longer need the additional features or want to pay as you go.

I haven’t tried downgrading a project with more than two datasets. If you do upgrade then downgrade later you should be prompted to remove a dataset.

But ultimately, I’m also curious what use case might need more than two datasets in a single project. Few projects short of upgraded multi-org shared spaces explicitly need more datasets.

Ah I see, thanks or problem is we are trying to use one sanity instance for multiple Shopify Plus instances (one for each country the manufacturer is based in, we are planning on using the experimental ‘Spaces’ feature to allow our client to switch between them without having to leave the interface. A lot of content will be the same across sites but enough data will be unique for us to have to split the data sets. Also as far as I understand the Sanity Shopify app can only sync one Shopify instance with one Sanity instance, but I notiuced that you can specify a dataset so we were hoping we could use datasets to manage the ecommerce connections. would be curious to know your thoughts as we are trying to improve the authoring experience without adding too much abstraction and we need to be able to localize the Next Js build as well which we know we can do pretty confidently with Sanity but managing a site with similar data including about 100 - 200 products per instance and a high volume of orders and changes seems tricky. Thanks for the insight so far 🙂