I’ve actually found a way to package my project with a lot of Groom assets. In my case, it had nothing to do with RAM, as I have 128 GB and I got a maximum of 60% usage.
This is how I was able to package it:
Step 1: Under Project Settings/Packaging/Directories to never cook: Add all directories with Groom assets
Step 2: Package the project as usual (without Groom Assets)
Step 3: Remove the directories from step 1
Step 4: Package the project again (now with Groom Assets)
With this simple procedure, I successfully packaged my project. Hopefully I can help someone with this