Thanks @adnan_alvee , yes, we did test Compatibility Mode. 

The output is a copy of files at a storage location, not a Unity Catalog table.

Context: We are setting up an external engine (duckdb) to read UC Delta tables through credential vending, which keeps grants and auditing in one place. The compatibility copy is invisible to UC, so the reader would authenticate to the storage directly, and we would be maintaining both a second copy of the data and a second access-control path for it.

So Compatibility Mode answers "give an outside engine the bytes" but not "keep the read governed by Unity Catalog", and the second part is the real requirement behind my question. That's why the CDF plus MERGE pattern into a plain UC-registered table is currently our leading candidate despite the bookkeeping it carries.

If you know a way to have the compatibility output registered in UC, or if there are plans for it to produce a governed table rather than a location copy, that would close the gap completely and I'd gladly take that path.