It's a simple case of ellipsis.

The "was" applies both to "given" and "displayed". So it is to be understood as "...was displayed". That is, as passive voice.

The object is Ju's art.

In active voice:

(Somebody) gave approval, and (somebody) displayed Ju's art.

It isn't being used without an object. It's in passive voice.

First of all, there's an implied "was" before "displayed". This disappears via a common mechanism in English grammar called ellipsis. So the remaining "was" effectively applies both to "given" and "displayed".

And both "was given" and "...was displayed" are to be understood as passive voice.

The object is Ju's art.

In active voice:

(Somebody) gave approval, and (somebody) displayed Ju's art.

It's a simple case of elision.

The "was" applies both to "given" and "displayed". So it is to be understood as "...was displayed". That is, as passive voice.

The object is Ju's art.

In active voice:

(Somebody) gave approval, and (somebody) displayed Ju's art.

It's a simple case of ellipsis.

The "was" applies both to "given" and "displayed". So it is to be understood as "...was displayed". That is, as passive voice.

The object is Ju's art.

In active voice:

(Somebody) gave approval, and (somebody) displayed Ju's art.