Fuck Trump. But it's not patently illegal. It's completely legal. It's only illegal if you're offering rewards to specific individuals. Otherwise every candidate offering anything material as a campaign promise would be violating the law. You're advocating for a legal standard that would allow Republicans to arrest any Democrat running on a platform of Medicare for All.
Remember, Biden ran on a very similar promise in 2020, promising specific stimulus payments to every American if elected. This is literally just a campaign promise, "if I win, I intend to give every American X."