I do not fully get the speed argument. If the dataset is small'ish, it does not significantly matter (given you only use the vectorized functions, of course). And if it's big data, I do not use pandas but Spark/a cloud data warehouse solution. For this reason I also do not get the use case for duckdb.
Beyond this, a dataframe api/syntax, compared to SQL syntax, is to me way easier to follow and to debug.
Beyond this, a dataframe api/syntax, compared to SQL syntax, is to me way easier to follow and to debug.