How is Metamask able to find NFTs that I've lazy-minted through Opensea if it doesn't exist on blockchain yet?

Sorry for this newbie question, but it's killing me. I'm trying hard to implement lazy minting but first I need to understand it.

I've just created and uploaded artwork to Opensea, using lazy minting. When I copy the tokenID and the NFT address and open it on Metamask (mobile version), Metamask is actually able to find & display that artwork !

If lazy minting includes creating a voucher and tokenID off-chain and storing it in a centralized location. (Which means the blockchain state does not get modified in any way), how on earth can Metamask locate the NFT and display it ? Does Metamask Mobile have some special integration to Opensea in any way (ie. They are looking up the artwork through Opensea API and not directly from the blockchain)?

Appreciate any help I can get in understanding this.

Ed