Recover data from broken iPhone 6
What matters most is the the motherboard and its components are in a good state, anything around (battery, screen, cameras, etc) can be replaced without touching the encryption chain. If it is broken (solder, contacts, etc), then you'll need to rebuild the chain; which is possible (check with harddrive recovery companies); if components are broken, you still can recover the chain with specialized services (using microscopes, white room and microelectronics) to get the AES key (I think hard coded/stored in the SoC/CPU if not in a security chip), and then I think only the memory chip is needed (which does not store the key).
If you can show a photograph of the motherboard instead of the screen, one might be able to tell more about the actual situation.