Having installed Drupal in DDEV on WSL2, as explained in the previous pages of this guide, here are a couple of best-practice things to set up before you continue with development.
This page explains how to install DDEV & Drupal in the Windows Subsystem for Linux (WSL2). It also offers some basic guidance on using and extending DDEV for Drupal projects.
Go to Firebase Authentication configuration (/admin/config/system/firebase_authentication)
Configure your private key path. E.g: ../../private/your-firebase-private-key.json
Access the REST resources pages and enable the following REST endpoints (the module already came with pre-configured settings - Don't set the authentication provider on these endpoints to the firebase_authentication)
Firebase Authentication user register
Firebase Authentication user login
Configure the permissions to use the REST endpoints above.