Microsoft"There doesn't seem to be an "Online" and "Offline" mode that the old MSfB store had although I'm not sure that's important with the new store."
I disagree. When deploying/configuring new PCs, you should deploy offline versions of all apps to avoid any reliance on Internet connectivity and third-party website access. Sure, online mostly works well, but when there is a glitch, you often don't know and you look foolish for deploying improperly configured devices. In general, it is not prudent to build your business on platforms and infrastructure that are not controlled by you, and run by people whom are not accountable to you.
Also, when you downloaded the app and test the deployment, then you know it will be deployed correctly - every time. If you are deploying online apps, then every deployment is downloading & installing an untested version. Who knows if the current version is really stable and will install properly? This is an uncommon issue, but companies occasionally release bad versions, then quickly release updates. If you deploy during that time, you get a bad deployment, and again you look foolish.
This concern may not apply to most people (even if it should), but it is important to many. This applies mainly to corporate controlled devices on-prem, of course.
