How about using an old phone? That’s what I do. I use xDrip+ on my phone, and so that my wife can check up on my bg’s,I use the “follow” function of xDrip on an old Note 2. It is set to landscape mode, nothing else on the screen, uses an xdrip widget and I also have a “dimmer” app to make it really really dim at night. Works great.
I installed a module so that the Note 2 can charge wirelessly, which makes it extra handy as we have about 6 wireless chargers around the house.
I wear a Ticwatch to bed with a Dexcom watchface which stays lit and on all night. So much better than checking my receiver on phone. And can answer phones, runs apps. Its terrific. least expensive watch out there too.