If you want to learn Unix/Linux, I'd install a VM and practice there. Working inside a container is OK, but you're slightly crippled, so you don't really learn. The Stairway to SQL Server on Linux has a level that's getting started with the OS.
http://www.sqlservercentral.com/articles/SQL+Server+on+Linux/176220/
There is also a good series on Simple Talk. Need to do a similar one here. - https://www.red-gate.com/simple-talk/sql/sql-linux/how-to-linux-for-sql-server-dbas-part-1/

If you just want to play with the applications, like Oracle, PostgreSQL, etc., containers make this easy. I'd run Docker for Windows with Linux containers and then pull the containers that you need for Oracle, etc.