Adding "unauthorized" apps to older Panasonic TV?

I have an old (2011) Panasonic Smart Viera Plasma TV.  It works great, fabulous picture, decent sound, etc.  But we're about to move it to another room where it won't be connected to any Firesticks or Chromecasts or Rokus, just the internet.

This TV has its own built-in app "store," but there's nothing worthwhile in there.  (In the Movies and Videos section there is something called "The Autism Channel" and a handful of foreign language choices and that's literally it.  It seriously almost looks like a prank.)

There's no Amazon Video, no Netflix, no Youtube, no network "go" channels, no nothing.  In fact, some of the apps that used to be there, including a couple I actually installed, have disappeared, so the pitiful choices are even worse than before.

What I want to know is, can I download and install apps and use them through the TV's standard app interface which are NOT found in the Viera Market app "store"?

I'm imagining a setting that allows downloading of unauthorized software and then an app which can download other apps, or something like that.

Is this possible?  Anyone have any ideas?  BTW, I am in the United States.