Every year I scan through their Google I/O website to see if anything catches my eyes, not many things they're presenting catch my eyes. I did look at Flutter 3, but probably won't try it out.
And the Google hardware ecosystem just does not appeal to me.
Being kind of a cheapskate, I've tried chromecast and the Amazon one and then bought an AppleTV device. I haven't had issues like I did with other dongle-like devices with having to restart them when there was a hiccup or crash of some kind - which is especially annoying when watching live sports.
I now have two AppleTV devices
(I use the word 'device' because they also have a streaming product called AppleTV+, which btw has some really good shows, and I think you can get the streaming service w/o the device)
You might want to check Videostream for Chromecast ? There's both a mobile app that links to your PC and also a desktop app. Last time I checked, VLC also allowed casting of videos on your PC(although iirc was more iffy with subtitles, etc) though not sure if there's mobile support, and I believe there are also other paid apps that can be used to cast videos.
If you're referring to seeing videos directly from a hard drive without a PC, a TV with usb support should take care of that (long time ago, I had even a Bluray player that had usb and was used in similar fashion to cast videos from a usb flash drive)
And the Google hardware ecosystem just does not appeal to me.