Hello. Is there any way I can sell items with custom displayname/lore via admin shops?

Nice. Thanks for the help

Yes, simply write the ID that /iteminfo provides on the sign or use the autofill functionality.

And how do I use the autofill functionality? And to clarify, what I want to do is to make it so players can buy the custom items from the admin shop.

By putting a question mark on the item line instead of the ID. Then it will ask you to click on the sign with the item you want to sell