If you have a serious connectivity, then maybe it would be more natural to use Odoo internally for in-store processes, and use another online store provider, like Shopify or WooCommerce.  If your online store volume would be pretty low, then the fees for those systems would also be inexpensive.

You can get Odoo on-premise to run the business, and periodically do a synch with your Shopify/BigCommerce/WooCommerce when the connection is stable, managing the online store separately.  You can get one of the connector modules to do a simple synchronization of orders.

If you have to synchronize two Odoo systems, on the other hand, I guess you'd need to either do a tedious export/import (likely unfeasible), or would need to build a custom integration (expensive).

Hello Brendan,   I believe you would need to have 2 odoo instances separate and make an interface to sincronize from the backend instance to the ecommerce instance.

is a good question, I hope some else could also help clarify this escenario.