For a short while, right after AMP started marketing the enclosed NM splice/tap some were suggesting this could be used and buried in these situations.
Knock out the old box, put in a splice up past the box and reinstall an old work ceiling box. Fortunately that didn't last long. The code 334.40(B) didn't change, only the marketing and literature that comes with the device. Now they only suggest this can be used in modular homes.
It is a distinction without a difference to me. Fires don't know the difference between stick built and factory built IMHO.
That still leaves us with few good options if you have no access to the top of the box.
