Sonnet eGFX and LG UltraFine 5K
I don’t have the unit to test, but would connect all the displays to the puck since it’s likely going to be the only active GPU.

The good news is it supports 4x 4K displays through one cable from the Mac to the puck - so a quick call to the vendor to clear your case (or Apple) might let you know.

I would worry about the LG display since it can’t take DP or HDMI input which is all the puck puts out, so you might need to connect it to the Mac and either hope it can drive it over TB3 or the integrated GPU can run the internal screen and 5K while the EGPU takes over the two 4K.

Sorry this isn’t definitiave, but I wanted to relay the research I have on this and clarify the issue on connectors according to the official specs:


https://www.apple.com/shop/product/HMT22ZM/A/sonnet-egfx-breakaway-puck-radeon-rx-560-external-gpu