He flew his kite on windy days but wished it was a drone. or He flew his kite on windy days but wished it were a drone.
WHICH IS GRAMMATICALLY CORRECT?
A. He flew his kite on windy days but wished it were a drone. Correctly uses the subjunctive mood; "were" and not "was".
The rule about the usage of was and were: use were with expressions that are hypothetical, wishful, imagined, desired, doubtful, and otherwise contrary to fact—that is to say, not real.
The key to understanding when to use was or were in a sentence is determining whether you need to use the subjunctive mood or not. A verb is in the subjunctive mood if it expresses an action or state that is not reality. For example, it might be hypothetical, wished for, or conditional.
Use were with the second person (you), the first person plural (we), the second person plural (you), or the third person plural (they).
However we need to make a choice about when to use was or were with the first person singular (I) and the third person singular (he, she, or it).
Use “Were,” Not “Was,” for Wishful Thinking
A sure sign that you should use the subjunctive is when the word wish is used. A wish is the desire or hope for something that cannot or probably will not happen.
I wish I were the winner of the Nobel Prize in Literature.
These phrases are never correct: I wish I was, I wish it was, he wishes he was, she wishes she was.
Ref Grammarly Blog
subjunctive; noun [ S ] LANGUAGE specialized, in some languages, a verb form that refers to actions that are possibilities rather than facts: Ref CED subjunctive