Do read the Get Started Guides (https://developer.ssg-wsg.sg/webapp/guides) on how to kickstart the app development with the APIs and within your own application/website.
Unfortunately I am not entirely sure how much customization you can do with Learndash, but as far as SSG-WSG APIs are concerned, you should at least be able to call the APIs according to the MTLS or oAuth requirements stated in the App Development guide: https://developer.ssg-wsg.sg/webapp/guides/6gvz7gEnwU2dSIKPrTcXnq
Do read the Get Started Guides (https://developer.ssg-wsg.sg/webapp/guides) on how to kickstart the app development with the APIs and within your own application/website.
Unfortunately I am not entirely sure how much customization you can do with Learndash, but as far as SSG-WSG APIs are concerned, you should at least be able to call the APIs according to the MTLS or oAuth requirements stated in the App Development guide: https://developer.ssg-wsg.sg/webapp/guides/6gvz7gEnwU2dSIKPrTcXnq