Anyone here use OneCast? Seems like a good way to share the living room when i just want to play something and the wife wants to watch something. Does it work okay with something like FIFA or Halo?

Microsoft has their version of streaming to mobile in beta now. It's not too bad. I don't recommend any quick response/fps games due to the inherent lag from streaming. Even driving games were lagging a bit too much for me when streaming from the console.

If you're a windows user, the console companion is a great portal that can stream as well. Lag isn't as bad, but still present.
https://www.xbox.com/en-US/console-companion-app

They've also got their trial of cloud streaming. sign up to be an insider and you can play games for free from their cloud server. all you need is your phone and xbox controller paired to your phone.

https://www.xbox.com/en-US/xbox-game-streaming/console-streaming

Good luck!

I have a 2mB/s connection at the house, which is fine for streaming SD tv shows, but thats about it. Definitely not good enough for game streaming, so it needs to stay local. The preferred use case would be on a phone, but theres a free trial on the macOS version so i may just see if i can get it running and go from there. Big issue i may run into is that it says you need to be online, but maybe thats just to register the software with the xbox. My router is nowhere near my media center, so i'd like to just have a spare router i have laying around thats not online to put in the media center and hardwire into the xbox just for this.

I've tried it. It's okay. Seems only good for offline games. I've tried multiplayer games and it's hit or miss.

Yeah this evening I ran my router over to where I could hardwire my Xbox and did a trial run with Halo MCC. There was some lag but not too horrible. Could definitely see it being a problem in multiplayer, but I rarely if ever do that since my internet is so slow.