Yes, QuickBooks Online has a feature where you can create a quote/estimate using only simple steps.
Please visit our QuickBooks page to see our basic explanation about QuickBooks and how does it work

Please visit our plans and subscriptions page to determine which Quickbooks version/plans are best for your company 
Or you can contact us to request a demo
Quickbooks data are stored safely in a bank level security cloud
quickbooks is available as Online Mac and Windows Desktop App update
The mobile app is only available in QuickBooks Online, and not in QuickBooks Desktop.
No, Odoo does not work offline and requires an Internet connection to access the data. Only the Point of Sales application can work offline after the initial synchronization.
There are 35 basic Odoo modules like HR, eCommerce, Sales, Inventory, and accounting.
Odoo online (aka SAAS) stores data in a  database and it is protected from access and not available.