To show the battery percentage in the top bar in Pop!_OS, you will need to use the GNOME Tweak Tool.
Installing the GNOME Tweak Tool
To get started with showing the battery percentage, you need to install the GNOME Tweak Tool using the following command:
sudo apt install gnome-tweak-tool
Once it is installed, open it up.
Showing the battery percentage
In the GNOME Tweak Tool, navigate to the “Top Bar” section, and toggle the “Battery Percentage” on.
You should now see your battery percentage in the top bar.