for a setup I need an extra telemetry output port
TELEM 1 I have RF design
TELEM 2 data for camera
then I have my data for my FPV screen.
Is there a connector that I can assign to an extra output so my OSD works on my FPV?
A yes and it has GPS on GPS1 and RTK on GPS 2
The cons port is serial 5 it can be used. Photo from craft theory
If your gps is a here2, change it’s setting to CAN… then you have another spare serial port…
You can also piggy back your OSD off your telemetry if you just have one way communication
no it is an older version. but piggy back? 
Yes most osd only needs to receive it don’t transmit. So splice in telem2 wire TX on cube side to RX on osd side
Use the tx out of the telem 1, add a split… take that to the RX of your OSD.
Tx from cube == RX into RFD900
RX into OSD