Saw this earlier and had to jump in because I went through this exact nightmare last summer! I was trying to coordinate a massive DIY solar generator build for a group trip and had about 35 different components in my cart—specific wire gauges, fuses, the works. I tried the extension route and honestly, looking at the source code of one of them made me physically cringe because of how they handle your session data. It is a total security mess! Basically, Amazon treats your cart as a volatile state tied to your specific login cookies. They dont generate a unique ID for the cart itself in a way that is publicly queryable through their standard API. Its actually fascinating from a data architecture standpoint, even if it is super annoying for us users! When you use those sketchy extensions, they are basically scraping your browser DOM and trying to re-inject those SKUs into another persons session. It breaks constantly because Amazon updates their site CSS all the time. I love digging into the mechanics of how these sites are built, and honestly, the way Amazon handles the shopping bag is very legacy-heavy and focused on individual security rather than social features. TL;DR: Amazon cart data is locked to your specific session cookies for security, which is why sharing it is such a pain. Sketchy extensions just scrape your screen data, which is super risky for your privacy and data security!

Amazons lack of a native cart API is honestly pathetic. Ive had issues with collaborative lists failing to track quantities, but thats basically the only safe workaround currently available.