@asn11Assuming that you have already explored GraphQL API, and it
doesn't fit your requirements.You can write your own custom model
exporter via extending ModelExporter, customize page.model.json as you
need in order to return it to an external API. ref - ModelExporter
(Apache Sling 12 API) Solved: Model exporter xml - how customize
response conten... - Adobe Experience League Community - 421026