Maybe / Maybe Not You will have to experiment.
I did look at the videos and Gimp can add additional channels, but not designated as "spot channels" as in PS. You can make one using a selection. In the Select menu -> Save to Channel or Right click in the channels dock for a menu. Experiment with that transparency setting.
No good exporting as a tiff, the additional channels are incorporated / lost in the image but a PS .psd might work.
This in a Gimp 3.0.4 and the only PS I have an ancient PS7
I did look at the videos and Gimp can add additional channels, but not designated as "spot channels" as in PS. You can make one using a selection. In the Select menu -> Save to Channel or Right click in the channels dock for a menu. Experiment with that transparency setting.
No good exporting as a tiff, the additional channels are incorporated / lost in the image but a PS .psd might work.
This in a Gimp 3.0.4 and the only PS I have an ancient PS7