My older tv is currently connected to Directv through the composite video cable connections. Would Roku work through a switchbox for the composite video cable connections?
Many do not work at all. Get yourself 2018 roku express, it has composite output, model 3910x. The newer 2019 express doesn't have the av output.
No current Roku offers analog video/audio outputs. The last one that did was the Roku Express+ (3910) that was released in 2017. Some users have been successful using an HDMI to analog converter, but others have had issues with them. The major issue is probably no current Roku supports a 4x3 screen. They are all expecting a 16x9 widescreen display.
Not certain why you mentioned a USB connection, but I've never seen any streaming device that was capable out sending video out a USB port. The occasional Roku that did have a USB port (such as the Ultra) can only use it for watching media from an external USB drive.