For reference,
autocancel animations go for 30 and for most characters they can be interrupted as early as 4 frames. (4 frames is so tiny that most people wouldn't notice it at first glance, after all, that is equivalent to a
fifteenth of a second.) Interrupting the recovery animation early IS a part of autocancelling.
Regardless I just thought I'd elaborate on what I said earlier, about how landing lag has already confirmed to be partially interruptible, with the level of interruption being dependant on what attack was performed.
Note: These are not frame-by-frame, they are simply slowed down.
So here we see the full animation of Link's down aerial landing lag. He then shields afterwards.
And here we see the animation being interrupted slightly earlier by a roll. Note how he bends his legs, but unlike in the first GIF he doesn't then straighten his body and lower his sword.