Simultaneous prefix + suffix LIKE '%abc%' can be sped up with gin + pg_trgm

Usage:

CREATE EXTENSION pg_trgm;
CREATE TABLE "mytable" ("col1" TEXT);
CREATE INDEX "mytable_col1_gin" ON "mytable" USING gin("col1" gin_trgm_ops);
EXPLAIN SELECT * FROM "mytable" WHERE "col1" LIKE '%abc%';

which produces:

                                QUERY PLAN                                 
---------------------------------------------------------------------------
 Bitmap Heap Scan on mytable  (cost=15.10..104.10 rows=400 width=72)
   Recheck Cond: (col1 ~~ '%abc%'::text)
   ->  Bitmap Index Scan on mytable_col1_gin  (cost=0.00..15.00 rows=400 width=0)
         Index Cond: (col1 ~~ '%abc%'::text)

which means that the query was sped up.

Notes:

• dedicated question: Postgres Select ILIKE %text% is Slow On Large String Rows
• PostgreSQL only uses the index by default if the search term abc has three or more indices (thus trigram): I want to search for 2 characters, is there any solution? (trigram index only works for minimum 3 characters)
• similar question: PostgreSQL index for like 'abc%' searching