This app was mentioned in 4 comments, with an average of 1.75 upvotes
If you build/run your presentation using Google Slides, you can control it wirelessly using your phone.
Why not use Google Slides? You can get it here. https://play.google.com/store/apps/details?id=com.google.android.apps.docs.editors.slides
Then you just have to open your PowerPoint and cast your screen.
Google Slides, Goggle's app similar to Microsoft Powerpoint
I suspect gmail is getting help from Drive (which includes slides).
You could get slides directly: https://play.google.com/store/apps/details?id=com.google.android.apps.docs.editors.slides&hl=en_GB
Or drive directly: https://play.google.com/store/apps/details?id=com.google.android.apps.docs&hl=en_GB
Or the microsoft powerpoint app directly: https://play.google.com/store/apps/details?id=com.microsoft.office.powerpoint&hl=en_GB