Function enable_click_request 

pub fn enable_click_request(
    input_mapping: Res<'_, InputMapping>,
    to_add: Query<'_, '_, Entity, (With<Focusable>, Without<On<Pointer<Click>>>)>,
    commands: Commands<'_, '_>,
)

Send NavRequests when an Entity is clicked, as defined by bevy_mod_picking.

bevy_mod_picking features

bevy-ui-navigation inserts the DefaultPickingPlugins. This means you can control how mouse picking works by… picking the feature flags that are most relevant to you:

Check the bevy_mod_picking feature flags docs.rs page for a list of features.

bevy-ui-navigation only enables backed_bevy_ui, when the bevy_ui flag is enabled.

Depend explicitly on bevy_mod_picking and enable the flags you want to extend the picking functionality to, well, 3D objects, sprites, anything really.