Probably the best solution would be some kind of defi contract. In general, every will/trust has an executor, but you could build it in a trustless way if all you need to transfer are cryptographic keys. For example, you could write a de-fi contract that would automatically transfer the keys or all of your currency in three days to the wallets of your beneficiaries. If you survive the surgery, you would have 3 days to cancel the contracts execution.