Postgres 14

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CREATE TABLE tbl(col text);
INSERT INTO tbl VALUES
  ('10_asdaasda')
, ('100_inkskabsjd')
, ('11_kancaascjas')
, ('45_aksndsialcn')
, ('22_dsdaskjca')
, ('100_skdnascbka')
;

CREATE TABLE

INSERT 0 6

SELECT col
FROM   tbl
ORDER  BY (substring(col, '^[0-9]+'))::int  -- cast to integer
         , substring(col, '[^0-9_].*$');    -- works as text

col

10_asdaasda

11_kancaascjas

22_dsdaskjca

45_aksndsialcn

100_inkskabsjd

100_skdnascbka

SELECT 6

SELECT col
FROM   tbl
ORDER  BY split_part(col, '_', 1)::int
        , split_part(col, '_', 2);

col

10_asdaasda

11_kancaascjas

22_dsdaskjca

45_aksndsialcn

100_inkskabsjd

100_skdnascbka

SELECT 6