Micropython supports some level of introspection.
On the REPL (Python shell) you can click TAB to see a list of completions, either for the LVGL module namespace or for specific functions/fields of objects/structs.
This can also be achieved with the
As you suggested, you can also look at
lv_mpy.json which contains most (but not all) of the API. The advantage of the JSON file is that it provides more detailed information for functions (types of arguments, type of return value etc.) which are not provided by Micropython introspection.