// The action callback function.
function my_function_callback( $features, $gateway ) {
    if ( 'my-gateway' !== $gateway->id ) {
			return $features;
		}
    $features[] = 'some-feature';
    return $features;
}

add_filter( '__experimental_woocommerce_blocks_payment_gateway_features_list', 'my_function_callback', 10, 2 );