It seems that Ford is getting a new trim level ready for all three of its trucks, the F-150, the Ranger, and the all-new Maverick, as it recently filed a trademark with both the United States Patent and Trademark Office (USPTO) and the Canadian Intellectual Property Office (CIPO) for the "Thunder" name. Ford previously used the Thunder name for a European Ranger model variant but these new filings would give each of the three trucks the Thunder name for both North American countries.
Admittedly, the fact that Ford trademarked the name doesn't actually mean it's definitely going to develop trucks with it. Automakers regularly trademark names just for potential future use, to keep other brands from stealing them. However, Ford has actually used the name before, so it seems likely it's trademarking the name in North America with the intent to actually use it. There's also the possibility that Ford could sort of rebrand the name for electrification.
Ford's previous use of the Thunder name was for the Ranger Thunder, which was a slightly more off-road-focused model variant of the European Ranger. Given Ford's recent interest in electric pickups, and the similarities in the Thunder and Lightning names, it's possible Ford could combine the two, creating off-road-focused electric variants for each of its three pickups. Ford has already announced that another electric pickup is in the works, following its F-150 Lightning, so it would make sense to start prepping electric model variants and trim levels for future trucks. While the name could be a bit clunky—Ford F-150 Lightning Thunder, for instance—it would be cool to see an electric pickup given the same off-road treatment Ford gives its gas-powered pickups.
Again, there's no guarantee Ford does anything with the Thunder name in North America. At this point, this is all just speculation. However, with brands like Chevy and Rivian already developing their own electric pickups, it would be wise of Ford to keep pushing for new and interesting model variants and the Thunder name might help do just that.