Here's two possibilities:
**Activist David Hogg (D-FL)/Montana Gov. Steve Bullock (D-MT)-297 EV/50.2%President Donald Trump (R-N.Y.)/Vice President Mike Pence (R-IN)-241 EV/48.3%**Assuming Hogg runs as DemocraticHogg would win his home state of Florida by appealing heavily to suburban liberal voters in South Florida, and some conservative-leaning independents on guns. He wins PA because of suburban white women and black voters.
Or:
President Donald Trump (R-N.Y.)/Vice President Mike Pence (R-IN)-390 EV/52.5%Activist David Hogg (D-FL)/Montana Governor Steve Bullock (D-MT)-198 EV/48.2%**Assuming Hogg runs as DemocraticTrump uses Hogg's gun control as a campaign strategy to defeat him in Middle America, especially places like Ohio, Pennsylvania, Michigan, and other places. Trump uses Hogg's gun control to smear him in Florida and wins in a bigger landslide and the popular vote than in 2016.