How to get pivot with no specific pattern

I am looking for a way to handle following pivot situation.

Example data:

Now I want to get this output:

I tried:

SELECT SUBSTRING(name, 1, 1) AS column1,
       STRING_AGG(name, ', ' ORDER BY name) AS column2
FROM info
GROUP BY SUBSTRING(name, 1, 1)
ORDER BY column1;

but I got:

I don't know how to remove 'A', 'B', 'C', 'D' in column2, is there any way?(BTW, I use PieCloudDB database, if you haven’t heard of it, you can use PostgreSQL to demo instead. Thank You!)

If column 2 don't have value, do you want to show record? if you don't want, you can try my way:

SELECT 
    SUBSTRING(name, 1, 1) AS column1,
    STRING_AGG(name, ', ' ORDER BY name) AS column2
FROM 
    info
WHERE 
    LENGTH(name) > 1  -- Exclude single-letter rows (like 'A', 'B', etc.)
GROUP BY 
    SUBSTRING(name, 1, 1)
ORDER BY 
    column1;