How to get the memory card out of a broken iPad ?

iOS/iPadOS is architecturally designed to protect the owners data. 

All locally stored data is encrypted; by design, the only copy of the encryption keys necessary to access local data are held within the Secure Enclave - the device security chip. The device Passcode unlocks the Secure Enclave, which in turn releases the encryption keys to the Operating System while the device remains unlocked.

Unless you are able to successfully power-on and enter the iPad Passcode, all data will remain encrypted and beyond reach. There is no removable memory - even through disassembly; even if you were able to physically remove memory from the iPad, you would not be able to access any of the encrypted data once separated from the host iPad’s Secure Enclave.

Your only hope of recovering any locally stored data is through restoring a pre-existing iCloud or iTunes backup to the repaired or replaced device. If you don’t have a backup, your data has been lost.

You don't.

There are no memory cards to remove in iPads. Never has been. Everything is integral with the logic board.

You restore lost data from your backup. I take it you do not have a backup? If you do not have a pre-accident backup, it is too late now to do so.

Backup methods for iPhone, iPad, and iPod touch - Apple Support

Long shot: If the iPad is showing signs of life, try connecting it to a computer. The pachyderm on the premises is the iPad will want you enter the passcode to trust, connect, and continue. If the screen is not working....🚽.