Icon sets
The picker doesn't ship any icons of its own. It reads whatever is registered with blade-icons, which means every kit you install shows up in the picker automatically.
Filament ships with heroicons, so that set is always there.
Installing more sets
There are a lot of ready made kits for blade-icons. You can install any of them via composer, for example:
composer require blade-ui-kit/blade-bootstrap-icons
That's all. The new set appears in the picker's set dropdown the next time you open it.
A full list of available kits is on the blade-icons website.
Limiting the available sets
By default, all sets that are registered in your application are available in the picker.
If you only want to offer some of them, pass their IDs to the sets option:
IconPicker::make('icon')
->sets(['heroicons']);
The ID of a set is the name it was registered under with blade-icons, not the prefix of its icons. For heroicons the ID is heroicons, while its icons are prefixed with heroicon-.
If you are unsure what a kit registered itself as, you can list all sets:
use Guava\IconPicker\Icons\Facades\IconManager;
IconManager::getSets()->keys();
sets() is not only a visual restriction. Icons from sets you excluded are rejected on submit as well, so you can rely on it.