Ok figured it out. There's a bug for sure. You need to have the URL in the box to activate the pin but hitting back clears the box and hitting enter goes to the site. If you visit the site and then go back, then hit the back button at the top of the screen. The URL should fill the box and the pin button should activate.

Okay I have found a full proof solution.

1. Download Cetus Play (Fire TV remote knock off) on your phone.

2. Download the Cetus Play receiver App on your Google TV.

3. Connect the two together. Voila! You can control your TV with your phone and the MENU (three lines) button works.

4. Go to the webpage you want to bookmark. Press the MENU button on your phone from the Cetus Play App.

5. Pin option should be white now, click. Done.

Are you using Firefox for Android TV. It should be fully remote compatible.

I got confused cos I thought I just replied to this post, realised you posted it in the Chromecast sub. For everyone else's benefit here's the answer I wrote..

The grid of shortcuts you see when you load it up is as many as you're allowed. I kept visiting the site I wanted to pin and then not figuring out how to, I guess that's your problem too. From the home screen go to one of the existing pinned tabs and remove it. You'll be able to pin your own in its place

let me start by saying sorry..

just received my Chromecast w/ Google TV the other day (amazing product) and had a few quick question. I would love Chrome, but it looks like Firefox is my only option..? I used downloader to install a few apps (mobdro, teatv ect) but I'm not sure how to Install a legit browser..

this is the only post I saw on my favorite site reddit so I figured I'd give it a shot.. what is best best way to install a real deal browser and is Chrome an option? can I somehow install an APK? is there a way to install The Google Playstore?

any advice is greatly appreciated 🙏🏽