Unfortunately, there’s no easy answer at this point. You either have to (1) climb a fairly large learning curve involving IPFS, Solidity, Vyper, Truffle, and the OpenSea SDK, (2) do something hacker-ish like I’ve described here, which itself isn’t perfect and also takes some time, or (3) manually upload all 10k, which also takes a ton of time (or, well, pay people to do any of the above for you). I hope that OpenSea will one day offer an API to mint and list, as I think that would be an elegant solution. But, for some reason, that’s not an option yet.