The bike in question is a stock 2020 Giant Contend AR 1: https://www.giant-bicycles.com/us/contend-ar-1. Per customer service, they don't currently sell and clip ons/clamps adapted for the aero-ish ovular shape of the "Giant D-Fuse Handlebar".

Question is, are there any options to get clip on aerobars onto this bike without changing out the handlebars entirely? I know there are some that use the stem rather than the normal points of contact on the handlebar, but I don't think there are any that work with the stock stem either. Seems like replacing the stem would be easier/cheaper, but I have no experience with clip ons that use the stem (are they any good?).

There are obviously a million different clamps and extensions online, and some of them look like they would work with a more oval shape, but it's hard to tell. Additionally i don't know if that shape would be able to bear the same tightness/load that a normal cylindrical shape would.