Xbox 360 games streamed through XCloud don't allow me to play online.

No, the Streaming app for xCloud allows for online play of those xCloud games or will allow you to stream your Xbox games to your phone.

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It could be that Microsoft could be about to make us pay for a feature previously allowed for FREE!!...

You are confusing the xCloud service with streaming locally.

Xcloud allows you to stream games you do NOT own to your console. You basically "rent" access to the games which run on server hardware somewhere in the cloud, and stream the video feed to any device that supports xCloud. Be it your home console, your tablet,
smartphone or whatever. It's like Google's Stadia or what Sony does to bring backward compatibility to some Playstation games.

This is vastly different to the home streaming that allows you to stream the video feed from your console that plays the games you "own" to a device that supports local streaming.

Unless you are trying to allow thousands of people to access your own console from the internet to stream your games to them, you are not doing anything similar to xCloud.

So don't make up some crazy conspiration theory like "Microsoft is taking away our streaming, so we have to pay to use xCloud"

Essentially it's a way for you to play your Xbox through the Cloud so you can use your phone or tablet as a mobile device to play your games.

You can find more information at https://www.xbox.com/xbox-game-streaming/project-xcloud

you cant, the xbox app that allows the streaming from the xbox one etc is only on windows. you could use xcloud but that is not the best and is only in beta at the moment through web browsers.

laptops, mac included also don't allow you to plug in any hdmi source to view on the screen unless you use a capture card and even then that would not be the best way to play.

Trying to play fallout 76 through game pass on my phone without remotely connecting it to a console

Playing Xbox games on your phone via Microsoft xCloud

Microsoft xCloud allows you to play games off the cloud rather than connecting you to your console. In fact, you don't even need to own an Xbox console to play games on Microsoft xCloud. You will however need a Game Pass Ultimate subscription