data.header_link is a TypolinkParameter object, always truthy — check the resolved URL instead (see frontend.html). {f:uri.typolink(parameter: data.header_link)}

Link: {headerLinkUrl}

Button text: {data.header_link.title}

No link set — button won't render

{data.pi_flexform.variant} icon: {data.pi_flexform.icon} ({data.pi_flexform.icon_position}) align: {data.pi_flexform.alignment}