You need Gamepass Ultimate for access to cloud gaming and then you need a support device, like an iPad or even better a PC with windows. You are right, you cannot start MSFS on the XBox in the cloud or maybe you can if isn’t actually installed. However that would not be useful for us here.
The performance of the system, you are using, doesn‘t really matter as long as your network connection is reasonably fast and stable. It works for me with an old laptop, Windows 11 and 16 MBit/s network connection. An iPad works for me as well.