Is this CheapESIM plan valid for Haiti if I cross the border?

No, this specific CheapESIM plan is designed exclusively for use within the Dominican Republic. Although Hispaniola is a shared island, the two countries operate entirely separate telecommunications networks. If your travel plans include crossing the border into Haiti, or if you are very close to the border, your connection will cease to function or switch to extremely expensive international roaming. For travel to Haiti, you would need to purchase a separate eSIM plan specifically for that country to ensure cost-effective connectivity.