I am trying to search for miniature receiver and transmitter for custom made drone/helicopter.

I have no special requirements outside of a size. Sure, the size doesn't matter that much in the remote controller, but in the drone itself, it should be as small as possible so the drone can be too.

Of course, I know about all these single board computers especially made for IoT purposes like: ESP8266, Raspberry Pi (Zero), Arduino MKR with WiFi, or even MAMBA F722 MINI, but all of them seem to be too large for its purpose - to build the smallest drone possible.

I believe that people who create these RC vehicles will know about something smaller. I really appreciate your answers.