https://www.wsoctv.com/news/local/police-treating-vehicle-ex...
The videos show a large explosion but there isn't a single window at the front of the hotel that shows damage.
professional fireworks are also regulated to minimize mass-explosion risk.
if fireworks were involved in the explosion, it would necessarily be an improvised device. achieving this level of explosion with consumer fireworks would be difficult. the fireworks are a red herring, imo.
According to this article, there was also "gas tanks and camping fuel" inside the truck.