Creating a vault using the existing Bitcoin protocol without relying on covenants is indeed a challenging task, but it's possible to implement some protective measures using multisignature (multisig) wallets and time-locked transactions. Below is simplified approach for additional security!

Multisignature Wallet: Set up a multisig wallet that requires multiple signatures (e.g., two out of three) to authorize transactions. This means that even if one set of keys is compromised, the attacker would still need access to the other set of keys to spend funds from the wallet.

Time-Locked Transactions: Implement time-locked transactions to add an extra layer of security. Time-locked transactions can only be spent after a certain period has elapsed. By setting a delay on outgoing transactions, you give yourself time to react in case of a security breach.

Emergency Recovery Transactions: Prepare emergency recovery transactions as your "countermeasures." These are additional signed transactions that you keep securely stored in a separate location, such as a safety deposit box or with a trusted friend or family member. These emergency recovery transactions can be used to reclaim your funds in case of a compromise or loss of access to your primary keys.

Regular Monitoring: Regularly monitor the activity in your wallet for any unauthorized transactions or suspicious activity. Set up alerts or notifications to notify you of any unusual behavior.

Education and Awareness: Educate yourself and others about best practices for securing Bitcoin wallets, including the importance of storing private keys securely and being vigilant against phishing attacks and malware.

It's important to note that while these measures can enhance the security of your Bitcoin holdings, they are not foolproof, and there is always some level of risk involved. Additionally, implementing these measures may require a certain level of technical expertise, so it's essential to thoroughly understand the process and seek assistance if needed. Overall, by combining multisig wallets, time-locked transactions, emergency recovery transactions, regular monitoring, and education, you can create a more resilient and secure Bitcoin storage solution without relying on covenants.