@Vinny, great! Thanks!

Does PX4 expect the radio link to come from the VOXL 2 IO expansion board or can the radio link be connected through a different connector, like "E" in the included diagram?

The VOXL 2 is compatible with TBS Crossfire radio receivers through the UART on J19 connector; however, the UART is needed to connect to VOXL 2 IO expansion board. The VOXL 2 IO expansion board has a dedicated connector for Spektrum receivers. In the VOXL 2 documentation, both Spektrum and TBS Crossfire are connected to the UART on J19 connector. Does this imply that the dedicated connector for Spektrum receiver on the VOXL 2 IO expansion board can be used to connect to TBS Crossfire radio receivers?
(VOXL 2 IO expansion board is necessary to connector to 6 external ESC's)

@Vinny, I am just planning at the moment. Where can I find an exposed 1.8V pin on the VOXL Microhard Modem Add-on with USB Hub?

@Vinny,
Thank you for your response. I am interested in the HW option and soldering to the TP29/TP28 pads. Just to verify, those pads do exist on the most recent iteration of the VOXL Microhard Modem Add-on with USB Hub. On the item page, the image does not show TP29/TP28 pads (nor TP41/TP40, for that matter); however, on the Microhard Modem Add-on datasheet they are included. See attached.

Item Page:

Datasheet:

Reading the documentation, the connection to an external flight controller requires the VOXL 2 USB3.0 / UART Expansion Adapter; however, the connection between the VOXL 2 USB3.0 / UART Expansion Adapter and the VOXL 2 utilizes the same connector that would be used for Microhard Modem Add-on with USB Hub.

Does the Microhard Modem Add-on with USB Hub expose a viable UART to connect an External Flight Controller to VOXL 2? Or is there another UART?

The external flight controller is Pixhawk 2.1/Cube Orange+.
Thanks!