Local / Personal library

Hi Glenn, Thank you for reaching out about library!
If you choose to publish the library to the team only, only direct members of that team can access those styles and components. Based on that, we tested on our end and could create a library for personal use as below.

Create a secret team on your own > Create a Project inside the team > Create a file inside the Project > From the file, publish library to everyone in the team

Then, you can add the secret team library asset from the library icon > [Your teams] tab > [Add to file] on the right to the asset to the other file

For details, please check here: https://help.figma.com/hc/en-us/articles/360040529593-Share-libraries-in-an-organization#team-only

Additionally, I found a similar request from the other community members here: https://forum.figma.com/t/one-free-library-for-own-account/2295
Free to check, if you are interested!

Hope it helps!
Thanks