We're busily working on some free galleries that we will make available on the website soon (e.g. Common slide layouts, Flags, Maps). We were pleasantly surprised to recently find 'maps' in PowerPoint 365. Hidden away in the 'charts' section of standard PowerPoint is a world map, linked back to Excel for some neat customizing. It's great for data overlay type slides but overcomplicated if you're just looking for more basic maps.
PowerPoint doesn't exactly make it intuitive (look in their help file for 'Create a Map Chart '). Googling for assistance we also found a good overview article from the folks at Bright Carbon: https://www.brightcarbon.com/blog/create-editable-powerpoint-maps/.