the only radio transmitters, also called remote controllers, that embed a fpv screen, for seeing what the drone sees, near the joysticks, instead of having to get obstructed vision by goggles,

that I found, are :

1. https://www.youtube.com/watch?v=df0Cvv3T69Y called fpv1 (i'm not interested into h7000 as it runs android and requires wifi rather than RC)
2. https://www.youtube.com/watch?v=XBbptOuXXdA called fpv2

However they only seem to be able to bind Hubsan drones...

1. Would it exist a way to flash them in order to make them run openTX firmware, or anything that could make them become universal controllers?

2. Alternatively, what parts from Hubsan should I buy if I want to put in my own custom drone build and be compatible with these ?

3. Can I build from scratch a controller with arduinos so that I could use openTX, embed an fpv screen, while still getting decent range (>5km) ?

the only radio transmitters, also called remote controllers, that embed a fpv screen, for seeing what the drone sees, near the joysticks, instead of having to get obstructed vision by goggles,

that I found, are :

1. https://www.youtube.com/watch?v=df0Cvv3T69Y called fpv1 (i'm not interested into h7000 as it runs android and requires wifi rather than RC)
2. https://www.youtube.com/watch?v=XBbptOuXXdA called fpv2

However they only seem to be able to bind Hubsan drones...

1. Would it exist a way to flash them in order to make them run openTX firmware, or anything that could make them become universal controllers?

2. Alternatively, what parts from Hubsan should I buy if I want to put in my own custom drone build and be compatible with the DIY ecosystem ?

3. Can I build from scratch a controller with arduinos so that I could use openTX, embed an fpv screen, while still getting decent range (>5km) ?