Hi anon777
The instructions found in the Electrum official download page will not work with Whonix. Other Whonix users have tried and failed.
Third party package manager such as pip not be used.
https://www.whonix.org/wiki/Install_Software#Avoid_Third_Party_Package_Managers
Manual software installation should be avoided as well.
https://www.whonix.org/wiki/Install_Software#Avoid_Manual_Software_Installation