Using your Amazon Fire TV stick you could watch out TV channels using your remote control. It will not work out of the box though. If you have a bit of I.T. competence and/or can follow instructions carefully then you can install Google Play app store, and then an app named "STB emu" and use it to watch our channels using your remote control (not via a web browser).
Important note. This was achieved using an external USB keyboard. We could not type details in STB Emu using the Amazon Fire without an external keyboard, there was a bug with the app not being 100% compatible with the Amazon Fire. So you should grab one of those for around £10 from Amazon, such as this one - having an external keyboard will give you the added bonus of making it *much* easier to type our IPTV server address and other details required to connect to our IPTV server, rather than trying to use the limited remote control to do so.
Although Amazon Fire runs on Android, they have managed to lock their box down so much that you are limited to the (rubbish) Amazon app store.
You can, if you follow the guides carefully, install "Google Play" on Amazon Fire and get access to almost unlimited apps.
Then, you could install STB Emu (which stands for "set top box emulator", it emulates a MAG IPTV box (these are designed to connect to IPTV servers so people can buy a box, connect it to their TV and use a remote control to watch live TV etc)
Here is a guide to install Google Play app store on your Amazon Fire device - https://www.howtogeek.com/232726/how-to-install-the-google-play-store-on-your-amazon-fire-tablet/
Once you have installed the prerequisites (Google Services Framework etc) and finally the Google Play store, use it to search for and install "STBEmu".
Once STBEmu is installed, follow our Android STBEmu setup guide