I have the same question.

Tengo la misma pregunta.

I think the POS module only save sale order in the browser cache, which mean that if you refresh the page, sale orders will be lost.

If you want to achieve the same thing, you'd have to manage your datas in javascript. When you finish "something", send the datas to odoo. If you don't get a response, then store the data, and periodically try to send them to odoo until you succeed.

I think you should also create something that could export those data to something more reliable than browser cache. I did not think a lot about this, but being able to export your data to a CSV file for example could be great. If you lose your connection, you export what could not be synchronized with the server, and you'll be able to import them later :)