F-Droid is an alternative to the Google Play Store that focuses on offering a catalog of open source software to install and update on your Android devices. Not all open source software is available on the Play Store, but might need to downloaded and installed as APK files from their websites. Instead, I find it easier to install and manage all these apps from F-Droid.
Install: F-Droid itself is not available on the Play Store. So download the .apk file from the website and install it on your device.
.apk file to a USB drive, plug that into the TV device, open a file explorer app, find the installer file and install it.Repository: The app pulls from a set of default repositories of packages, one of which is https://f-droid.org/repo. The app also allows addition of other repositories at Settings -> Repositories -> New Repository. One of the repositories that I found useful is IzzyOnDroid F-Droid Repo. IzzyOnDroid also provides a simple web interface to view the various popular repositories and their app listings.
Manage apps: Apps installed using the app and those installed directly from APK files (but the app is present in F-Droid) can be viewed in F-Droid. Go to Settings -> Manage installed apps to view the apps individually.
Update apps: Find the updates for your installed apps under Updates.
Find apps: The best way is to use the search and hope something reasonable shows up. The apps can also be explored in the various categories, though I found this tiresome. There are also recommendations of the best apps like this one.