Ask in a the Microsoft Powerpoint for Mac forum over at Microsoft. Maybe they know of an option. A wireless mouse might work, but I’m not at all current on PowerPoint. (This is centrally a PowerPoint app support question, too.)
My recent presentations have all been done using Keynote from an iPhone or from an iPad. Watch to advance slides. I can hand off the entire iPhone as needed too, or the iPad can stay propped up on the podium with the speaker notes visible. This with AirPlay directly, or with AirPlay to an Apple TV on the podium wired. Or classic presentation directly with wiring and Watch, if I’m not adding to my step count while presenting.