Export and Import Modern Sharepoint list

The simple answer is that the list can be copied, but the Power Apps custom form does not automatically come with it. A list template is therefore not enough on its own.

1. In the production site, create a new list by choosing New > List > From existing list and select the development list. This is an easy way to copy the columns and views.
2. Before making changes, open the form in the development list through Integrate > Power Apps > Customize forms. Keep it open as a reference, or take screenshots of the important controls and formulas.
3. Open the new production list, choose Integrate > Power Apps > Customize forms, and build the form there. For a simple form, recreating it is usually quicker and more reliable than trying to export and import it.
4. Test the production form with a few sample items before users start using it. Check required fields, choice columns, attachments, lookup fields, and any buttons that start a flow.

If this form will need to be moved between development and production regularly, it may be worth building it later as a separate Power Apps app. For a one-time move, copying the list and rebuilding the custom form in the production list is normally the clearest approach.