When you register a sidebar in WordPress, is it possible to choose in what order it appears in the admin

Sidebars are output in registration order, which is implicitly captured by how they are added to a $wp_registered_sidebars global.

This can easily be manipulated, for example following code will move first sidebar to the start:

add_action( 'register_sidebar', function ( $sidebar ) {

    global $wp_registered_sidebars;

    if ( 'first' === $sidebar['id'] ) {
        $sidebar = $wp_registered_sidebars['first'];
        unset( $wp_registered_sidebars['first'] );
        $wp_registered_sidebars = [ 'first' => $sidebar ] + $wp_registered_sidebars;
    }
} );

register_sidebar( [ 'name' => 'one', 'id' => 'one' ] );
register_sidebar( [ 'name' => 'two', 'id' => 'two' ] );
register_sidebar( [ 'name' => 'first', 'id' => 'first' ] );