Add site title to the navigation. See https://gist.github.com/generatepress/9f99bbfa532ea4f9eafb6bd238b8cc9a for necessary CSS.

gistfile1.txt

add_action( 'after_setup_theme', 'tu_navigation_as_header' );
function tu_navigation_as_header() {
	remove_action( 'generate_header', 'generate_construct_header' );
	add_action( 'generate_inside_navigation', 'tu_site_title_navigation' );
}

function tu_site_title_navigation() {
    ?>
	<div class="site-branding">
		<p class="main-title" itemprop="headline">
			<a href="<?php echo site_url(); ?>" rel="home">
				<?php bloginfo( 'name' ); ?>
			</a>
		</p>
	</div>
    <?php
}