Bulk Upload NFTs to Opensea and other marketplaces through blockchain - https://www.youtube.com/watch?v=wxynC7aL5k8

MyNFT.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.15;

import "erc721a/contracts/ERC721A.sol";

contract MyNFT is ERC721A {
    constructor() ERC721A("MyNFT", "MNFT") {}

    function mint(uint256 quantity) external payable {
        // `_mint`'s second argument now takes in a `quantity`, not a `tokenId`.
        _mint(msg.sender, quantity);
    }

    function _baseURI() override internal view virtual returns (string memory) {
        return "ipfs://bafybeifgxh2lo3jpx6xg2bl3wlnifgpahcdvmktl42jz7d7m7x7y6yap3i/";
    }
}