A cat will melt due to a miss fire but generally does not break apart, thermal cycles / thermal shock will break a cat.

At least on my 97 SL320 ( M104 inline 6 with ME 2.1 injection ) , if you lift an injector wire / short a plug wire to create a miss fire, that cylinders fuel will be cut off after a few seconds to prevent cats from melting. This strategy might be on your system as well.

Some cars get really fussy when a cat isn't exactly as OE and throw a catalyst efficiency code.

I'd split the exhaust and clean out any loose parts. Mom and Dads 99 Blazer has a breaking apart rear cat and the pieces now reside in the muffler. . .where they continue to do their cat job and are heating the muffler up enough to balloon it. It still passes cat efficiency OBD tests so I leave it go.