I discovered this awesome script (it's in the iNav GitHub, so not really that hard to find) that shows a screen full of useful telemetry data. Included in this is the number of satellites your GPS is currently locked on to, so no need to keep checking through your goggles to see if you've got that fix and arming is enabled. All the data could be manually put on to a telemery page, but it wouldn't be laid out so well, nor contain as much data on one page.
For this to work, you must have SmartPort set up on the Flight Controller and enabled telemetry, have LUA scripts enabled on the Taranis, and have discovered all sensors of the model on the Taranis.
Step 1 - Download the LUA script
This is a really easy step. Head to https://github.com/iNavFlight/LuaTelemetry, click the green Clone or download &arrd; button, then click Download ZIP. Save the file somewhere useful, like a Taranis LUA folder.
Step 2 - Make sure you can run LUA scripts on your Taranis
Open up the latest version of Open TX Companion, and click the gear icon near the top of the screen. This shows the options you have enabled when you download the firmware for your Taranis. If you have LUA and LUAC ticked and you've flashed your Taranis with these settings, you're good to go. If not, you'll need to download the firmware and update your Taranis.
LUAC isn't needed for this script, however there are other scripts that are so large they won't run unless you use the compiled version, so it's worth installing it now, just in case this script grows too large to be run uncompiled.
Step 3 - Get the script on the Taranis
Open up Windows Explorer and navigate to your downloaded of the LUA script zip file. Extract the file and enter the extraction folder. In there you'll see a folder called TELEMETRY, right click and copy this folder. Switch on and Plug in your Taranis, and select SD card mode. Back on windows, navigate to the Taranis SD card, and enter it's SCRIPTS folder. Paste the TELEMETRY folder in to the SCRIPTS folder. Once copied across, unplug the USB cable.
Step 4 - Setting up the screen on the Taranis
On the Taranis, click the menu button and select the the model on which you want to enable this screen. Long hold and release the page button to navigate backwards through the menu until you reach the DISPLAY page. Next to Screen 1, select SCRIPT, then in the new box select iNav. Exit out of the menu completely, then hold down the page button to show the new iNav telemetry screen.