can we make a single app in C3 to showcase and play multiple games?

I thought about looking into this, and it looks like loading a website from a zip file into an iframe is way more complex than I thought XD

I mean, it's possible but it's a bit ridiculous. The main issue is that since the files are not served from anywhere, you need to create in memory URLs to all of them and then update all the places that use URLs in your index.html with your in memory ones, so the iframe can find them.

It seems like it might work for simple use cases, but a C3 export is not a simple use case and I wouldn't be surprised if the approach runs into problems.

Yeah, serving complex content like exported Construct projects requires being served normally. That means https: on the web, or in Cordova or desktop exports it internally uses a protocol like app: that works similarly. It doesn't even work properly on file:.