Something like that:
add_filter( 'wc_zap_mirror_wp_query', function( $args ) {
$args['meta_query'] = array(
'relation' => 'AND',
array(
'key' => '_stock_status',
'value' => 'instock',
'compare' => '=',
),
array(
'relation' => 'OR',
array(
'key' => '_wc_zap_disable',
'value' => 'yes',
'compare' => '!='
),
array(
'key' => '_wc_zap_disable',
'compare' => 'NOT EXISTS'
)
)
);
return $args;
} );