MetaMask – How to Generate Account Pictures for Enhanced Security

Metamask doesn't store keys or any data of wallet on server , actually the mnemonic generated by metamask when you create the wallet has the capability to generate the private key, public key and ethereum address .

This mnemonic is called BIP39 seed phrase,and it can be used to regenerate the private key of your wallet , private key can generate the public key and public key is used to generate ethreum address. So this feature is not specific to metamask , it is the property of BIP39 mnemonic to encode the private key of your wallet. That's why you should keep your mnemonic pass phrase secretly .

For further information you can access the link :- https://silentcicero.gitbooks.io/pro-tips-for-ethereum-wallet-management/content/ethereum-wallet-basics/using-seed-phrases-to-create-ethereum-accounts.html

There is an online tool which you can use to regenerate all the information of your wallet using the seed phrase:-https://iancoleman.io/bip39/

According to this Official source, it actually seems possible to see NFT on mobile app only.

"Please note that while you can add NFT's as custom tokens in the extension, you will not be able to see them natively in the UI."

Also, Metamask warns : "Please remember that some NFT's will not show up on the mobile app under Collectibles, or may not show up correctly."

In the end, my NFTs are on my Ledger and I can't connect my Ledger on mobile app without compromising my private key.

The only easy way I found is to see them in maketplaces, like OpenSea.

But maybe some NFT Museum apps, like https://www.nftmuseum.art/, will come online soon ?