No problem! I'm in the same boat since I have to deal with Android TV as well but it sucks. It's hard to find an open source alternative for anything. It's a sealed box unless you install a custom ROM which is not the case for most of the devices, especially smart TVs. You can sideload apks over adb though, if you can find an app that is not on Google Play. If you don't use a Google account, you have to sideload everything anyway (which is what I did last time).

There is TV Bro as @Babalugats suggested but it's not comfortable as Browser and it's not so up-to-date. Most of the open source apps you'll encounter have the same issue. It's not that developers don't want to develop apps for Android TV, it's just Google (and manufacturers) don't let them to play around freely.