The answer is: Experience Fragments (XF) cannot be assembled server-side in EDS like we are used to with classic AEM.
Possible alternatives are:
- Expose XFs via API and load them client-side in EDS
- Switch to EDS fragments, which are again client-side rendered
Therefore, this might be challenging for clients who are used to using many XFs. Moving to EDS requires redefining and simplifying how content is stored and authored.
Hope it helps someone,
Daniel