My original support ticket submitted to Mojang, updates to follow:

Upon purchase of the newest texture pack, he was unable to install it due to lack of storage space. The Nintendo has over 100GB of storage space, and the texture pack was 666MB. After hours of troubleshooting online between Mojang, Microsoft, and Nintendo FAQS as well as user forums, I have hit a roadblock that made the game unplayable.

I have:
-Uninstalled & reinstalled Minecraft multiple times
-Deleted all save data multiple times

There have been 1-2 times where the newest texture pack actually downloaded and imported, but inevitably failed with error: hbui.CreateNewWorld.resourcePacks.unspecifiedErrorBody

After that, I just deleted the save data and tried again without any texture packs. Every single time I load up the game now, and log back into my Microsoft Minecraft account, my "save data" shoots back up to the 2 GB limit. This not only causes us to be unable to load the texture/packs or skins, but also prevents us from creating new worlds.

Update: Mojang me to clear Marketplace Cache & restart the game several times until resolved. This did not fix the issue, and they told me to submit this bug.

The texture packs causing the issue are Earthy Texture Pack by SuperBusyMC and Simplistic Future Texture Pack by Giggle Block Studios.