Postgres does even better and it's available right now. No virtual column needed.

    CREATE TABLE t1 (data JSONB);
    INSERT INTO t1 VALUES ('{"column1":1234}');
    CREATE INDEX t1column1 ON t1(data->'column1');
    SELECT * FROM t1 WHERE data1->'column1' = '1234'; // not sure about data type

I would not call an index format which gets slower with growth "better". And that vacuum issue on JSONB scales with your data size.