We ended up using a reverse proxy since we wanted each product page to have a separate URL. Basically /shop/* would resolve to our React app, which rendered the correct page based on the URL. You could configure this pretty easily using NGINX or Apache, but our customers were pretty technically unsophisticated so it was too much work for them to do it this way.
In the end, we built a Wordpress plugin since it turned out that most of our customers used Wordpress. This plugin acted as the reverse proxy. We went a step beyond this and did some cool stuff to let them use a shortcode to render our eCommerce menu within their existing Wordpress template.
One wrinkle with ditching the iFrame was getting our CSS to not conflict with their CSS. I ended up putting our stuff within a shadow DOM, which was a bit of work but ended up working pretty well.
In the end, we built a Wordpress plugin since it turned out that most of our customers used Wordpress. This plugin acted as the reverse proxy. We went a step beyond this and did some cool stuff to let them use a shortcode to render our eCommerce menu within their existing Wordpress template.
One wrinkle with ditching the iFrame was getting our CSS to not conflict with their CSS. I ended up putting our stuff within a shadow DOM, which was a bit of work but ended up working pretty well.