In 2d space I have two cameras with different field of view ($40$ and $46$ degrees in my example) and have some distance between them.
Is would possible to describe this distance using just this two numbers? And using degrees as dimension of result?

It's theoretical question. If it impossible it is okay.
Given the information you have, it is impossible to calculate the distance. For example, if you move one of the cameras, the field of view is still the same, but the distance has changed.
However, if you extend the lines coming out of the camera until they cross and form a triangle, then you only need the distance of one of the extended lines. Then you can use the sine rule to find the distance between the two cameras.