@Parough3
Unfortunately, TVs don't have any apps in them that monitor data usage, or at least not that I know of. You may want to look through the apps that you use for the TVs and see if there are any settings adjustments that can be made to help reduce the amount of data they can use. There may be areas in those apps that show much data theyr'e using, but again, I'm not sure. And keep in mind that streaming uses a lot of data. Netflix's rates are 700MB per hour in SD and 3GB per hour in HD, with the other streaming services being similar, give or take a little.
I believe the iPhone X should have an app called "Activity Monitor", and in that app there should be a Network tab that can show you how much data the phone is using, whether via WiFi or the cell network itself, though of course the WiFi is what we're concerned with. There should also be other apps that you can get from the App Store that can monitor the phone's data usage, and probably in a more thorough way than the Activity Monitor. You may want to take a look at what's available. You should also check to see if it's connected to and utilizing the iCloud, as that can chew through a LOT of data.
As for the Chromebook, I can't look apps up in Google Play without having one, but there are likely apps there that can monitor your data usage. I don't know if the Chrome OS has a built in monitor, but it may.
Though you should be able to find data monitoring apps/programs for both your iPhone and Chromebook, the TVs are going to be the tricky ones. Unfortunately, it's very possible that the only way you could really know for sure how much data they're using is by using a 3rd party router that has the capability of monitoring data usage by device, and they aren't exactly cheap. Plus, they usually have to have their firmware flashed to a 3rd party type, like DD-WRT or ASUSWRT-MERLIN. They can do a great job, but again, it's not cheap (upwards of $200 or more).
In the end, the best thing you can do is find apps for the two devices on their apps sites (App Store and Google Play), and then be careful with not only how much you stream, but what definition you're streaming in.
Lastly, just in case, if you have satellite TV it's best to not connect the receiver to HughesNet, as satellite TV receivers can chew through data like there's no tomorrow, even if you never watch anything "on demand" (stream) with them.
Others may reply with good data monitoring apps to use with your iPhone and Chromebook, but always make sure to check the apps out before installing them.
