Nobody can gain access to your iPad without successfully entering the correct device Passcode - and for this, there are a limited number of tries before the iPad will automatically become disabled. As such a brute-force attempt to access a working iPad, by guessing the correct passcode, is highly unlikely to be successful. Only if your device Passcode is known to whoever finds your iPad will any locally stored data be at risk of discovery.
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.
If an incorrect Passcode is repeatedly entered, the Secure Enclave automatically wiped and the device disabled - an operation that erases all stored encryption keys. This is known as a crypto-erase. Once erased, all locally stored data is permanently beyond reach and cannot be recovered.
If the iPad is dead, there is no opportunity to access the passcode or decrypt data; your data is safe.