How can I integrate an Experience Builder app into another hosted custom web application that I developed?
I Jake,
In order to embed an experience in another custom web application, you can do the following:
1- Deploy the experience in your web server
https://developers.arcgis.com/experience-builder/guide/deployment-topics/
2- Embed the application using, for exemple, the html <iframe> element
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe
Regards,