Hello,
It would require some customization of your product page.
Afterwards, you can see to use some product custom fields ; so you can store the links in specific columns that you will be able to access in the product page.
But the display of your "dropdowns with links" is too specific to be provided by a custom field.
If you have some development knowledge, you can also see to create a "plugin custom field" to have a plugin providing a specific interface for edition and display.
But using classical custom field with a view override for the display will be easier to implement.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.