You can of course also get to know a company as a "visitor" or "guest". This is called work shadowing ("Hospitation"). People engaged in work shadowing do not work, but get to know the company and work processes by observation.
Get to know a lot of companies
Work shadowing is not employment, consequently it does not need to be approved by the immigration authority ("Ausländerbehörde"). There is no maximum period for work shadowing. However, because no salary is paid and it is not an internship or intended to replace a job, work shadowing generally only lasts a few days.