Your old Android tablets running KitKat 4.4 (if you still have them) are now compatible with the Home Remote. Support for it was added to Home Remote version 18.104.22.168.
I went through the Android code the past couple weeks to make it KitKat compatible. For the most part, all of the features are supported however there is definitely 1 thing that will not work. HTTP/2 is not supported on these older devices. The only Home Remote integration that requires HTTP/2 is Alexa so most other integrations should work fine.
Yes, the Home Remote is now 4.4 compatible but it will probably run better on a newer Android device. If you have the option, choose something newer.