Hi there,
you can add your button html ( or shortcode ) for example:
<a href="#">Button</a>
inside the Mobile Header using a Hook Element and selecting the inside_mobile_header
hook.
Note: this the mobile-button
class will be our CSS selector.
The use this CSS to hide it on static navigation:
.mobile-header-navigation:not(.is_stuck) .mobile-button {
display: none;
}
It will need some other CSS to position it – i would need to see the GP site setup to advise on that.