I was looking for a player that had this functionality when I switched to Linux. Finally settled on Clementine which has both a library & "file browser" mode.
In the browser mode you can just right click and add the folder to your playlist. Just like in foobar2000.
Consider switching to strawberry, it's a fork of Clementine. Clementine hasn't really been updated in many years (aside from auto translation merges and a typo here and there).
In the browser mode you can just right click and add the folder to your playlist. Just like in foobar2000.