Has anyone tried this? Google Chromecast with Google TV is great for streaming, but is no Nvidia Shield. But if you have an old android phone you could connect to your tv as a set top box, you could save a lot of money.
Has anyone tried anything like this?
A long time ago its was possible to install an apk to make an android device become a chromecast receiver. That was the closest to what you proposed. No longer possible.
Besides, Google wants to sell those devices. Even if you made it happen, they would shut it down in a hurry.
I absolutely support your point, but sadly that goes a long way.
Even the raspberry pi can get Android TV, the point is there are so many different models of Android phones, and among them so few want to have their phone as Android TV that no developer even thinks about it.
This will be far more difficult than porting LineageOS to your phone, as it also involves challenges that many people have never faced.
It's not just because it saves a lot of money, it's because it's better for the environment, I also have a lot of outdated phones, and for phones they're terrible, but for Android TV, they're the best devices, even 32 GB is also hard to find in mainstream streaming devices, but phones that are seven years old have 32 GB of storage.
We can repurpose these devices, maybe the battery is an issue, but it would be nice to get power directly from the AC adapter.
In short, there are so many things that need to be done, but almost no one does it, because it is easier for them to throw these obsolete phones away, throw it into the environment, and let the future pay for the consequences of today's actions.
First of all you wont find android tv build for you "old phone", second of all very little and only high end phones support hdmi over usb c output. Thirdly would be the problem of remote. I can think of hundred other issues. No, its not a good or doable idea.