Suspending notifications has been built into Windows 10, if not from day one, for a long time now.

If the goal is to suspend them during a PowerPoint presentation (or anything you're duplicating to another screen [often a projector]) the first method mentioned is best.  If you just want to shut up notifications for some set duration the Quiet Time option is preferable.

https://www.windowscentral.com/how-disable-notifications-while-presenting-windows-10

(Be aware that if you are using a ad blocker the page above will have a pop-up appear over it, which you can (and will have to dismiss) using the controls on it to either continue with your adblocker active or whitelist the windowscentral site).

This is also a topic that would have been best suited to the Chat Subgroup, since it's definitely not about NVDA.  But the proverbial hammer is not yet being brought down.  I'm hoping that folks will start asking themselves the question, , “Is what I’m about to ask related to using NVDA directly to accomplish something, or to control NVDA itself?,” independently and choose posting venue according to whether the answer to same is, Yes (main group), or "No" (chat subgroup).
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Brian - Windows 10 Pro, 64-Bit, Version 1809, Build 17763  

Growth for the sake of growth is the ideology of the cancer cell.

           ~ Edward Abbey