Update on my efforts on finding a different way of making a "have all items" code. As suspected, it's going to take a ton of codes. I've given up on it, but will post what I found in case I decide to come back to it later and finish it. No need to test these unless you're just curious.
These are raw/unencrypted...
Pirates of Dark Water
These codes can be turned on at anytime during game play. If you turn the codes on while the game is paused, you may need to un-pause and re-pause to see the effects.
04BA1E:6002 Enables the cursor/bracket in the pause menu.
04C028:6002 Adds the pictures of all the items in the pause menu.
04C092:7809 + 04C094:4E71 Adds a value of 9 to every item in the pause menu (can be modified to any value you want).
04B9E6:6002 Allows you to move the cursor up to where the items are so you can select them (in the pause menu).
00FF4C:6002 Lets you see which item was selected from the pause menu when you return to the game.
As you can see, every tiny little thing needs a code. Will be waaay too many by the time I'm done.
Will go back the the single code I made earlier and see if I can improve that one.