How to find out if a cell is (visibly) blank in LibreOffice Calc?

In LibreOffice Calc the =BLANK() formula will only return TRUE on cells with the underlying datatype ”blank”. In other words: If the cell contains a formula that returns nothing (or if it contains the empty text string), =BLANK() will be FALSE. Is there a way to check if a cell contains displayable content, such as a text string or a number? In the screenshot below, the =ISBLANK(B3) formula in C3 returns FALSE, as the cell contains a formula returning nothing. How would I go about to check is a B:B cell is ”blank” in the sense of not containing any data?