You don't need Sidequest to install *.apk programs on Oculus.
Since Oculus is just an Android device, you can use adb (tool provided by Google, used by Android developers, see some more at https://developer.android.com/studio/run/device). It requires some setup the first time you use it (you need to put your device in developer mode, install adb, and either install the right drivers if you are on Windows or setup udev rule if you are on Linux), but once you have that, you just need to connect the device via USB, and call ` adb -s <device_name> install <apk_name>.apk`