A NE555 could be sufficient and even more reductionist. =;-) Circuit example https://theorycircuit.com/ic-555-ic-741/adjustable-duty-cycl...

A CD40106 could do the same and would even be more reductionist (and uses less current).

This does the typical "two short buzzes with a break in between". I think that would be hard with a singe NE555, and of course much more annoying/complicated to fine-tune.

Also, the random delay between the notifications.