I saw a lot of people come into trouble about how to get the SHA1 key after watching Getting started with Firebase in Unity (2019). Here is the process I used. keytool -list -v prints both the SHA1 and the SHA256.

Open CMD and go into the .android folder:

cd .android

Then:

keytool -exportcert -keystore debug.keystore -list -v

Hit enter. It asks for the keystore password. The debug keystore password is android. Type it and hit enter. Nothing shows while you type. After enter, the certificate block is on screen, including SHA1 and SHA256.

First posted on DEV, 26 July 2022.