OcBinaryData VS My-Simple-OC-Themes

HfsPlus.efi is missing, get that from this link and then put it in your Drivers folder: https://github.com/acidanthera/OcBinaryData/blob/master/Drivers/HfsPlus.efi

Fixed loading macOS with legacy boot without Apple Secure Boot: there is a new PE (Portable Executable) loader that broke legacy boot, blocking the loading of legacy drivers as HfsPlusLegacy and preventing OpenCore from booting on legacy systems when Apple Secure Boot is disabled. With this fix, legacy boot can work with or without Apple Secure Boot. This issue was detected after version 0.8.8 was released. While you are on 0.8.8, you must download the new versions of the drivers HfsPlusLegacy and ExFatDxeLegacy (the one/s that are necessary), available in Acidanthera. This is not required if you are on OpenCore 0.8.9.

Update Resources as well: https://github.com/acidanthera/OcBinaryData

Check if you have the latest resources Folder (included in OC Binary Data)

Copied from the latest OcBinaryData

I'm able to download and open up the zip as instructed, but as far as dropping the "ExFatDxeLegacy.efi" file into the right location on my ESP (which I understand to be my boot drive, where OCLP was originally installed), I'm at a total loss.

Have you tried downloading the version from https://github.com/acidanthera/OcBinaryData ?

This is intended for theme artists, OpenCore team has no new icon for these tools. I guess chris1111 has something new in his github. Look at

chris1111 - https://github.com/chris1111/My-Simple-OC-Themes Huge repository. Collection of backgrounds and icons, very customizable. He has also created a tool to help you generate your own set of icons: https://github.com/chris1111/OpenCanopy-Generator

There are already some OpenCore 0.6.8-capable themes designed by others users. For example, Default-StarWars by crhris1111 or BsxDarkFence series by blackosx, all of them high quality themes.