[wrxtasy]

Is there any Android TV box (chromecast, kodi, netflix...) with refresh rate working and good upscaler for SD /720p content ? (1080p output tv)

Kodi High quality upscaling needs one of three things:

1) A media player that has working, reliable auto Resolution Switching AND a TV that has inbuilt high quality Hardware upscaling, for non 1080p content... OR

2) A media player that has the CPU ponies to CPU Software decode non 1080p content AND has CPU Upscaling like Lanczsos3-optimized working... OR

3) Media player hardware that already does high quality hardware upscaling of non 1080p content.

If you only want cheap DRM copy protected Netflix streaming get something like Mi Box or a FireTV Stick 4K.
Chromecasting may or may not work properly, results may vary.
Android TV Chromecasting is Not as reliable vs using actual Chromecast hardware.

Be aware the Mi Box has DD+ audio dropouts when using the Netflix App. 2.0 audio is OK with that combo.

If MyCanal works on a FireTV Stick 4K, it will be a more reliable combo for Netflix and Dolby audio, a more powerful Chipset as well.

Android Kodi is a convoluted mess if you want to access CPU software decoding AND CPU Software upscaling.
It really is not user friendly at all vs Linux / LibreELEC / OSMC / CoreELEC Kodi Leia.

Auto resolution switching (1080p > 720p) does Not work at all on a Mi Box. It can only go up 720p > 1080p for Kodi Leia.
There is a bug with Kodi Leia auto Refresh switching on the Mi Box, it always switches to the highest Resolution the TV can output when also Refresh switching.

Personally if you already have auto resolution switching working (SD/720p <<-->> 1080p) when using Kodi on a RPi, on a 1080p TV - stick with that and let the 1080p TV do the upscaling. You then meet Option (1) above.