How to show two columns in separate rows, avoid duplicates and omit empty entries

I got two tables which I joining the query.
The joined table has two columns which I need as separate rows in the query-output; duplicates must be omitted.

So far I got it.

If one of the second column of the joined table is empty, this row must also be omitted.
I am failing with this requirement.

create table article (id integer, artnum varchar(100), artname varchar(100), PRIMARY KEY (artnum));
 insert into article (id, artnum, artname) values (1, '100', 'apple');
 insert into article (id, artnum, artname) values (2, '101', 'banana');
 insert into article (id, artnum, artname) values (3, '102', 'clementine');
 insert into article (id, artnum, artname) values (4, '103', 'dragon fruit');
--
create table supplier (id integer, supartnum varchar(100), supplier1 varchar(100), supplier1name varchar(100), supplier2 varchar(100), supplier2name varchar(100), PRIMARY KEY (supartnum));
 insert into supplier (id, supartnum, supplier1, supplier1name, supplier2, supplier2name) values (1, '100', '23', 'DZ', '42', 'VZ');
 insert into supplier (id, supartnum, supplier1, supplier1name, supplier2, supplier2name) values (2, '101', '42', 'ZV', '23', 'DZ');
 insert into supplier (id, supartnum, supplier1, supplier1name, supplier2, supplier2name) values (3, '102', '23', 'DZ', '', '');
 insert into supplier (id, supartnum, supplier1, supplier1name, supplier2, supplier2name) values (4, '103', '23', 'DZ', '23', 'DZ');

select artnum, artname, --supplier1name, supplier2name,
(unnest(ARRAY(SELECT DISTINCT e FROM unnest(ARRAY[supplier1name,supplier2name]) AS a(e)))) as "suppliercombo"
from article
join supplier on artnum = supartnum
;

Result:

| artnum | artname      | suppliercombo |
| ------ | ------------ | ------------- |
| 100    | apple        | VZ            |
| 100    | apple        | DZ            |
| 101    | banana       | ZV            |
| 101    | banana       | DZ            |
| 102    | clementine   |               |
| 102    | clementine   | DZ            |
| 103    | dragon fruit | DZ            |

The first appearance of atrium 102 (clementine) with an empty suppliercombo hat to be omitted.
I tried using Union All but failed, because its already a 300line-sql which would be duplicated..

Example is also on DB Fiddle

> If one of the second column of the joined table is empty, this row
> must also be omitted. I am failing with this requirement.

The query can be written as in DB-FIDDLE-1

select artnum, artname, suppliercombo
from (
   select artnum, artname, 
   unnest(array_remove(array[supplier1name, supplier2name], '')) as suppliercombo
  from article
  JOIN supplier ON artnum = supartnum
) t1
group by artnum, artname, suppliercombo
order by artnum;

This gives me the correct output as :

The above query can be also simplified using union as in DB-FIDDLE-2

select artnum, artname, suppliercombo
from (
  select artnum, artname, supplier1name as suppliercombo
  from article
  join supplier on artnum = supartnum
  where supplier1name != ''
  union
  select artnum, artname, supplier2name as suppliercombo
  from article
  join supplier on artnum = supartnum
  where supplier2name != ''
) t
group by artnum, artname, suppliercombo
order by artnum;

This also gives the expected output as above.