Can you use Salesforce sandboxes?

I would like to try out flows in my sandbox before deploying to production.

I can’t seem to find a way of configuring the salesforce endpoint to use instead of

Our Salesforce Export unfortunately can’t be configured with your sandbox. Our recommendation would be to add a row filter step at the very end to only update one entry in Salesforce. You can keep updating the row filter step until you feel confident in your results. Once you feel confident, you can remove that row filter step entirely and export everything to your Salesforce instance.