Sure thing there's an app called "send files to tv", install it on both devices, later use a file explorer downloaded from play store to install the app in question

Install X-Plore from the Android TV Playstore and then you can Sideload to your hearts content:

http://www.lonelycatgames.com/docs/xplore/wifi-share

You'll need to enable developer options to do this. It should be accessable via settings / about and then click on the build number until you get a pop up stating it's done.

I may not be exactly right on where build number is kept as I don't have one but I've seen the process in YouTube so it shouldn't be too hard to find.