Microsoft has added a new feature to its 365 Apps which should make it easier to keep staff working even if they can't connect to the internet, plus another option for shared devices.
Microsoft's apps generally require customers' devices to connect to the internet at least once every 30 days to sign in to stay up to date. If the device does not connect to the internet in that time, the device's licensing token is not renewed and Microsoft's apps go in to 'reduced functionality mode' for that device.

Your business may need to enable your workers to have secure access to your organization's on-premises and cloud-based information, tools, and resources from their homes.
For IT professionals managing onsite and cloud-based infrastructure to enable worker productivity, this solution provides these key capabilities:
You can enable all of your workers to stay productive from anywhere with these devices:
A modern device, such as a Surface laptop and Windows 10, which has the features, security, and performance to access Microsoft 365 cloud apps and services directly over the web.
Any device including older laptops or desktops used from home, which can access Microsoft 365 cloud apps and services indirectly through a quickly deployed Windows 10-based virtual desktop. This option provides high performance, strong security, and simplified IT management.