If you don't mind having non-straight double quotation marks, then you can use CHAR(147) / CHAR(148) / CHAR(152)
Formula: copy to clipboard
=CHAR(147)&"content"&CHAR(148)

will give “content”

Formula: copy to clipboard
=CHAR(152)&"content"&CHAR(152)

will give ˜content˜

Is that something you can work with?