You'll have two options. The first is to purchase another hardware wallet and restore your seeds using it. The second is to download one of the popular wallets out there and restore it. Most of the hardware wallets generate BIP39 seeds, but you'll still have to know the derivation path for your specific wallet. It shouldn't be a problem because that is public information.
OK,but what if OP doesn't have money to purchase another hardware wallet or he goes to a country,where hardware wallets are not sold?
Now, that means you have successfully demonstrated how Bitcoin cannot be confiscated. That's a good way of illustrating how Bitcoin is indeed about complete ownership. You own your Bitcoin. In that way, your worth is kept safe and untouched despite a situation when the economy and society collapsed. The next steps that you will do are the ones detailed above my post.
But I will ask you, what exactly do you mean by societal collapse? Because if it is a situation when the entire society is reduced to rubles and people are going back to the primitive ways, then I'm afraid Bitcoin is also rendered worthless.
Bitcoin CAN be confiscated.This has been proven many times.Just ask the FBI or any Ministry of Internal Affairs in almost any country in the world.
Hypothetical::So the worst has happened, economic and societal collapse. My family escapes to a bitcoin-friendly (or unfriendly) jurisdiction. I do not have my hardware wallet. Before fleeing I smashed it to pieces, least it's confiscated. Seed phrase memorized and ready to go. Now what?
OP,why do you have to smash your hardware wallet?Can't you just take your wallet with yourself?
What do you mean by "economic and societal collapse"?A war situation?A natural disaster?
In case of economic collapse there are two case scenarios:
1.You get flat broke and unemplyoed,which means that you have sell your BTC,in order to survive.
2.Facing hyperinflation,which also means that you have to sell your BTC,in order to have food on the table.
Both case scenarios have nothing to do with you smashing your hardware wallet and memorizing a seed phrase.