Bridge camera specs

[Journeyman]

I would like to ask about bridge camera specs. All related to 35 equivalent.
Speaking roughly rather than a specific figure.
Most crop sensor cameras vary from from 1.4 up to 2 or so. Depending on sensor size.

I don’t really take crop factor when thinking of interchangeable lens. 400 is 400, 300 is 300 etc.

My query relates to maker’s published figures, particularly for bridge cameras.
With bigger zoom cameras how are the 600 or even 2000 figures reached. My reading is that a camera with a zoom of 600 is achieved by using a 300 lens and multiplying by the sensor crop factor. eg. 300 x 2 crop sensor is a 600 lens.

Interchangeable lens crop factor of 1.6 (Canon)
400 x 1.6 is 640. I believe that to get to a genuine 600 - 300 + 2X converter

The reason I ask - does a Canon 1.6 x 400 provide the same zoom as a “super zoom” 600 set up? Are the zoom factored figures accurate in this sense.

Thinking interchangeable crop factor camera + 400 lens v’s Sony RX10.

Thank you, pardon any rambling or in accuracies, I have found it difficult to find good info on this subject. Kind regards, Journeyman