Netflix and youtube use its own keyboard, no third party keyboard or gboard.

I have been using Rii X8+ for my Mi Box S ATV and the keyboard input works on most of the apps including Netflix. I have come across only one app that I installed that doesn't recognize the keyboard inputs. The battery lasts for 2 months and it is rechargeable.

I'm having similar problem. Google remote keyboard works only on main search, doesn't work with netflix or youtube.

You have two workarounds:

1. Use wireless keyboard via USB adapter. I have small Dell multimedia keyboard with trackball. You get mouse cursor as extra navigation. What is most important, keyboard input works on all apps including netflix and youtube. Too bad that google remote control app can't fake keyboard inputs same way as "physical" keyboards
2. Use "Serverless Bluetooth Keyboard & Mouse for PC/Phone" app from google play store. It works exactly the same way as physical wireless USB keyboards but via bluetooth. This app has touchpad, keyboard and multimedia keys (home, back etc..) in free mode, much more in paid version but the free one is enough for what you need. Notice: This app doesn't work on my old Huawei MediaPad T3 tablet (bluetooth pairing issues) but works like a charm on Samsung Galaxy S9 smartphone

Interesting fact: Year ago when I bought my TCL Android TV, I have installed app "Magiconnect TCL Pilot" which also has remote keyboard and it worked. Well, worked very bad, lags while typing and often eated chars, but worked somehow. Tried it again recently (after few major Android TV updates) and remote keyboard doesn't work at all same as other similar apps ("Google Remote", "Roku" etc)