In this situation being unassuming may be the best option. A hardware wallet in a safe is too conspicuous, attracting lots of attention and giving the impression that you hold a lot of bitcoin. You can keep a wallet software on your phone or desktop without anyone you live with having an idea. Also do not talk about bitcoin or investments.

If you must use a hardware wallet you can keep it in a bank vault for a charge.

You should be more careful with your backups as they grant direct access without the need for a password. You should store where they are written down outside that house if you have the means to and have an additional passphrase that is not written down with the recovery phrase. This helps for security and plausible deniability.

So you mean a joint family system, right? I would like to ask a little question, as I also live in a joint family system. If you are afraid of such things, then first don't tell anybody that you are buying Bitcoin. In my case, in my whole family, only my father knows that I am holding an amount of Bitcoin, and after him, no one knows about it. And why i only told him about it because of some personal reasons. And likely, if you want to stay safe, then give priority to privacy first. And don't disclose much about it in front of a lot of people for your own best. This is my point of view, and you can relate your own scenario to it accordingly if it helps you. DYOR!

A classic "friend of a friend" thread. This is a much-discussed topic on this forum, but asking for advice at this stage of Bitcoin's history, and perhaps where everyone is over 18, is redundant.

Anyway, it's one thing to ask for help getting hardware, or how to follow online security parameters, that's understandable, but asking for help hiding something, well, why not? But it's always a very personal matter. If you live near a river, it's not just about being clever at hiding it from humans; you also have to know how to protect it from Mother Nature.

A lock is useless unless you have the key, without the key, a lock cannot be used in any way. So where and how you keep your wallet is not important, you need to pay the most attention to keeping the seed phrase safe. Of course, do not keep the wallet in a place where it can be damaged or stolen. Even if it is stolen, your bitcoins will be safe if the seed phrase is protected, in which case you will only lose your wallet.

Your main focus to keep your bitcoins safe will be to store the seed phrase. Since the seed phrase can be easily written down on a small piece of paper or a small piece of metal, you can store the seed phrase safely even in a crowded house.

An airgapped device may be the best choice for your situation, or you can even use a software wallet that will be easy to keep safe on your mobile.

No matter what you do, storing the seed phrase is important. For extra security, you can use a passphrase that is separate from the seed phrase.

It sounds good to install an alarm, but it is still too dangerous, because the electronic device will not be fully functional and requires regular maintenance to work normally, I would not keep it in a safe, I would keep it underground and bury it safely

You know better the exact condition of your household and if you are experienced enough on different storage medium, you will know that it is more important to secure your device first and also avoid any one again interference using it as well as where you keep your private keys as well as seed phrase, this shows that you will always be in possession of anything that has to do with your wallet without living it behind, but if what you have as your asset is what much more than the risk you can't to lose staying together in a household, I would rather prefer or suggest you rent an apartment for privacy.

Put a password and a passphrase, that’s usually enough so far it’s hidden. The other part you need to worry about is the backups (seed and passphrase).. 

Those are  much more important than the hardware wallet itself.. I will suggest just bidding it in your wardrobe, you don’t need some kind of crazy sound alarm, doesn’t do much incase of theft either .

You can get a small safe instead that can be password instead,  if you still can’t stop scratching your head over it..

It's funny because your friend is probably making it obvious that there is something there by putting his hardware wallet in a safe, which would draw attention. But to me it's not a bad thing if that's how he wishes to keep the hardware because in an organized family, they are probably supposed to know what privacy is. But I would say he should keep it somewhere that wouldn't draw attention. However if someone was to find it in the house by mistake and doesn't know what it is then that's perhaps another huge risk because even if they don't know it exists, it doesn't stop the curiosity. Either way, it would be risky at home, so he should find somewhere else, like the bank to keep it for max security. That's all...

Typing your seed phrase into a computer every time you use Sparrow wallet?  That is a terrible idea.  It exposes your secret phrase to keyloggers and malware, making your funds trivial to steal. Paper only protects your seed phrase offline; the moment you type it onto an internet-connected device, your security drops to zero.

I like your thinking and raised some valid points too!!

First off hardware wallets are no longer the safe haven we all thought they were and maybe hiding the private key or passphrase in plain sight should be the way to go...all those extra measures of alarms and all that just attract unnecessary attention which would certainly motivate someone to look into what you are protecting.

Maybe consider sharing the secret with the beta half to avoid having all this burden,if you trust nobody perhaps an implant would be considered if we want to go to the extremes.