Having multiple library cards is great when it comes to reading; it gives you a much richer selection of resources and more chances for any given work to be available.
California libraries often offer cards to an California resident; this may include online registration for a temporary card (normally 1-3 months) which can be converted to a regular card if you visit the branches.
This spreadsheet from 2024 lists libraries and their associated networks to help find library cards. Create a copy of this spreadsheet and use it to find local libraries. When traveling around California it can be useful to check your destinations to see if getting a card would be useful.
Each extension needs to be configured with your libraries. Library Extension focuses on showing you books on a variety of sites; Available Reads is focused more on a better experience with GoodReads specifically.
Website: libraryextension.com
This enhances GoodReads more specifically; it displays on your Bookshelf pages, which can be good if you use bookshelves actively.
Website: GoodReads Extension