So，how to store the seed?
Write it down on paper. Job done.
That is exactly what is needed, and additional security procedures will most likely add more risk and less security.
You can also use a passphrase and write in a different piece of paper if you are worried about the security of the paper.
Hi, different people have different opinions on it.
Actually, in my opinion, "write it down on paper" is idealism. I think it is not the best way. To be honest, for now, fewer and fewer people use paper. I think we need to find a new solution to help people store their seed.