Hi mycc,
as you already know, you cannot add a hyperlink to the cell itself. Only to its contents.
All solutions I could think of are more or less not very flexible or automatic in case you must change the width or the height of the cell.
[1] Add a right indent tab at the end of the text and add a hyperlink to the text.
This would take care of the width of the cell minus the indents of the cell and the paragraph.
[2] Anchor a graphic frame to the first text insertion point of the cell and add the hyperlink to the anchored frame.
Size it to the height and the width of the text cell.
Unfortunately out of the question:
For cells that are defined as graphic cells you could add the hyperlink to the graphic frame inside the graphic cell.
FWIW: Adding text frames to graphic cells is not possible. Or if you somehow accomplish this, e.g. by scripting, it will crash InDesign in the moment when you duplicate a table by whatever means: Duplicating the page the table is on, moving the page to a different document, copy/paste the table, the text frame holding the table etc.pp.
Regards,
Uwe Laubender
( ACP )