Yes, it is actually possible, the product level stock is stored in the '_stock' custom field. On the Advanced Options -> Content panel you can make use of that with the Advanced Description field: https://i.imgur.com/oI3HddO.png
My configuration on the screenshot is this:
Which translates to: 'Stock:' text in bold, followed by the value of the stock field, then a line break, then the default description.
It looks like this: https://i.imgur.com/rPTDUHw.png
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