Do OpenCart 3 extensions work in OpenCart 4?
The simple answer is no. OpenCart 3 was based on OCMOD while OpenCart 4 uses VQMod to make changes to OpenCart. In fact, OpenCart 4 is a total redesign from the ground up, so there are many file changes that make the core significantly different from version 3.
When you go to purchase our extensions, you will see which ones support either or both versions.