T-Mobile where is your support for Kyocera phones?

The manufacturer is responsible for when a device gets an update.  All T-Mobile does is offer up some bloatware and does a little testing for carrier aggregation.  If something doesn’t sell too well, you can’t expect T-mobile to keep offering their products.  I don’t know if that is the case but that is how sales work.  Some carriers also negotiate exclusive agreements for devices.  I would suggest contacting Kyocera to find out when your device is going to get an update.  Android 7 though…  I’m guessing that product is long beyond the end of life cycle.