NAND flash devices in the interior of the device will likely survive.
That's the program store which is important. This will be reverse assembled to investigate software attack surfaces and vulnerabilities.
Broad structure will be apparent, which will tell what types of SIGINT they were trying to gather.
Pieces of antennae will be obvious which will give frequencies.
Reverse engineering the build of the device itself will provide intel on the level of sophistication of Chinese builds and device capabilities.
The DoD/NSA doesn't need to have a running version to extract tons of useful information from this thing.
Landing it in the water means that more of the microstructure(chips, pcbs, wiring, RF elements, etc) will survive intact.