Smash it with a hammer for a minute or two, then microwave the chunks.

That’ll probably do the trick.

Alternatively, smash it, eat it, shit it out later at not where you live.

Better if you always carry a pocket lighter.

You can just throw it and nobody can find it especially if you are outside.

As long as the silicon got snapped and not just the softer plastic around the silicon.

If it’s actually important data that a nation state would want, most of the data could still be read off with an electron microscope.

Just encrypt your data and don’t tell them the key that you’ve memorized. If you have trouble forgetting things, use a hammer.

I absolutely would not count on a snapped in half MicroSD to protect the data that’s on it from someone determined to find out what it was. You don’t even know if you actually managed to break the memory chips themselves or just the connections between them, which with time and patience and the right equipment could be reconnected, and even if the chips are broken a great deal of the data on them will still remain intact, etched in silicon for eternity and vulnerable not only to current technology but also future technology.

Your goal is turning the data stored on your MicroSD card into a puzzle. A 2 piece puzzle is likely quite solvable even today. To properly vaporize the card and make it actually unreadable you’d likely need to do some experimentation and try things you would potentially have access to in war like fire, gunfire, explosives or corrosive chemicals, some combinations of which may serve to well and truly annihilate any hint of structure. The question is how many tiny pieces can you break that MicroSD card into, if that number is a human-countable or even human-comprehensible number like the number of pieces a document typically gets shredded into, then it’s probably not safe enough to consider it reliably destroyed.

If people can tape back together shredded documents to get the basic idea of what was written on them, someone can likewise theoretically repair your MicroSD to get a large proportion of the stored data from it if they are absolutely intent on doing so. It’s probably a lot of work, and maybe not even a not-worth-it amount of work depending on how important your data might be, and there might be a substantial amount of data unrecoverable and missing, but it can be done. Unless you make it a puzzle with so many pieces that doing so is mathematically implausible and just as likely to be an incorrect reconstruction of data that might say anything the reconstructor imagines it does, without actually giving them any confidence that it is real and correct. The only thing that’s certain is that 2 is probably not a good enough number of pieces to rely on for that to be the case.

As an alternative to the fire/gunfire/explosives/acid style methods, you might also use sandpaper (would take awhile), or better yet a grinder tool of some sort (dremel, angle grinder, bench grinder) to give yourself some confidence that the card has truly been turned to a pile of arbitrary dust. Even then, I’d still concerns as the data density increases, a single speck of MicroSD dust from a 1TB card shredded into millions of pieces might still contain 1 MB of data – that’s an awful lot of text and even potentially some images if it can be decoded. They really prove surprisingly hard to destroy. Electrical attacks, even Microwave ovens, reportedly have mixed results and don’t sound like reliable approaches either.

If you can get it to a molten state, that’s your highest confidence method. Silicon has a melting point of 1,414 °C, good luck.

The way to do this is plausible deniability. There is software that allows creating an encrypted volume with two passwords, resulting in two different decrypted volumes. So you give the duress password and there is no incriminating data on there.

For example grapheneOS also has a duress pin that wipes the device.

Why are you so concerned about the destruction of data? This is the 3rd post in 2 days from you along these lines

No, but you can smuggle them by eating them.

Soldiers don’t look for your sdcards, they shoot people. If you are planning on moving through block posts where your things are cheked it’s better for you not to have weird sdcards either broken or not. But you can have one in your phone. There are ways to hide encrypted data so it won’t be detected e.g. veracrypt hidden volumes.

Snapping sounds like a real faff.

Keep them all in a special plastic box that is inside a powerful electromagnet.

Push button and a field that is strong enough to damage the cards almost instantly and over a short time would generate enough heat to physically damage the cards.

With enough power and time you could turn them into one hot blob that wouldn’t even be recognisable.

So near instant data damage and then physical destruction probably before someone can work out what’s going on.

Just swallow it?

Since it got answered already encryption is also another layer that can be implemented to further make it unrecoverable