This is a functional and scalable nft contract implementing Azuki's ERC721A. https://github.com/chiru-labs/ERC721A
This contract has public sale, whitelist sale, and owner mint features. Test it out in remix and adjust to your specs.
I have commented on essentially every line of code and provided resources for further information within those comments.
If you appreciate this resource, check out my NFT project Techno-Feudal Citizens. www.technofeudal.com