You might be aware of a little thing we run called APK Mirror. It's a site that hosts (safe) free APKs so you can sideload them instead of waiting for staged rollouts. There are a few ways you can upload your APKs to the site, including the ML manager app. An update today (in beta) makes that even easier with multi-APK uploads.
ML Manager isn't just for APK Mirror (you can save your APKs anyplace), but we've worked with the developer to make uploading to APK Mirror an option. This update to v3.1 beta 2 is mostly about APK Mirror.
Added option to upload multiple APKs to APKMirror.
To upload multiple APKs to APK Mirror, simply long-press or tap the icons of the apps you want to share. Then, tap the 'plus' action button and pick the upload option. You will need to add a name and email to the upload before sending, but that only takes a few seconds and you can help out your fellow Android enthusiasts. You can get the new version of ML Manager on APK Mirror (duh). It'll come to the Play Store later.