I'm a big fan of Google Photos and Chromecast, taking a lot of photos and videos to view them on our home 4k TV. I always felt sad that I can't view my content in original quality though.
Here's my solution to the problem:
- Get a Windows Mini PC with a decent hard drive
- Install Google Backup and Sync on it, have it download and sync your Google Photos content to that hard drive
- Install ArinaCast on it (requires VLC, ffmpeg and imagemagick to be installed manually)
- Control what Mini PC is showing on your TV via your smartphone by going to http://192.168.0...:6567
- Optionally, use Chrome "Add to Home screen" for easier access and a full-screen experience
It's amazing when you can get closer to the TV screen and see every little detail on your photos.
Cheaper Mini PCs can sometimes struggle playing back original files, especially 4k / poorly compressed ones from home cameras. Playing with VLC settings or getting a more powerful device can help with that.