I was thinking something along the lines of storing your backup in a safety deposit box that contains a device that detects light that has the ability to alert you if light is detected. The device could have a long battery life and may be attached to the back of the container inside the safety deposit box.
Check out the Haven app, for android. It uses any android phone and it's sensors. Most phones have cameras (for light) and acceler---xxx the GPS thingy and a magneto-compass thingy. Whatever it's called, it can detect light or if the phone is moved.
Problem is battery life. Even if you attach a large power bank, it will eventually die.
Can probably use the cheapest Samsung J6 or something $100 phone, put it in ultra-low-power mode ... safety deposit boxes are usually dark, you can probably place it in some other location that has a window for sunlight and use a solar charger. Charges the phone during the day, runs on battery at night ... if it's within range of cell tower you can have it on the lowest prepaid plan and you'll maybe get an alert if something moves.
I understand you live in a very different part of the world than where I live. I think it would be interesting to one day visit your country as a private citizen in possession of a modest amount of cash. I also understand you are in a unique position for people in your country and might be able to protect private keys better than most other people in your country because of your unique situation.
I've moved quite a bit away from there, it's not a secret where I am, but rather not make it public, OpSec and all that. There are local exchanges and almost like El Salvador some merchants accept bitcoins, (some accept altcoins / shitcoins / erc20 tokens) ... I don't have access to my imaginary bunker, but something I'd like to personally build where ever I end up living.
I do keep a house in that country since it was cheap to buy and maintain. It does not have a basement, but it has a small back yard, so I can bury something there. Actually, it would make more sense to just keep whatever backup seed metal plates inside that house. ... hmmm... 3rd world problems eh..
BTW, don't bring too much cash, just enough, the rest you can bring as bitcoin and exchange that once you are in the country. Actually, you can probably bring in $10k USD cash no issues and then use local money changer or banks to convert to local fiat money. If you're staying longer than 90 days, you may need a visa or something. Otherwise, tourist visa on arrival is good for about that long.