Compatibility for Alembic cache in Unity is not a simple yes-or-no result. For feature support, list which features survive unchanged, which are translated, and which need a fallback.
For Alembic cache in Unity, classify each important feature as preserved, translated, approximated, or dropped. Test the same file in both directions so a successful open does not hide data loss.
Build a compact matrix showing what imports natively, what is translated, what needs setup, and what is unsupported. Apply this feature support guidance to the actual Alembic cache in Unity delivery path.