Making SQL query dynamic

The dynamic sql below is building the conditional sums from on a reference table with the categories.

SET @sums := (
SELECT GROUP_CONCAT(
CONCAT(
', SUM(CASE WHEN category_id = ', category_id, 
' AND `status` <  80 THEN 1 ELSE 0 END)', 
' AS `', category_name, ' En cours`', CHAR(10),
', SUM(CASE WHEN category_id = ', category_id, 
' AND `status` >= 80 THEN 1 ELSE 0 END)',
' AS `', category_name, ' Resolu`', CHAR(10)
) ORDER BY category_id SEPARATOR '') as sums
FROM categories
);

SET @dynsql := CONCAT('SELECT', CHAR(10), '  bug.project_id', CHAR(10),
', COUNT(bug.id) AS Total', CHAR(10),
@sums, 
'FROM bugs bug', CHAR(10),
'GROUP BY bug.project_id', CHAR(10),
'HAVING COUNT(bug.id) > 0;');

-- SELECT @dynsql AS dynsql;
PREPARE dyn_stmt FROM @dynsql;
EXECUTE dyn_stmt;
DEALLOCATE PREPARE dyn_stmt;

Demo on db<>fiddle here