Question about Zotac AMP Box Mini

As far as I know, there are egpus with enough space to fit 2 gpus and use them together. But I doubt that you can use 2 separate egpus together. At the moment I can only think of the sonnet echo 3 that goes in this direction and that would only support 2 singleslot gpus and also only has a 300w power supply. I would also personally advise against it, as thunderbolt 3 already limits performance with one gpu, a good gpu in an enclosure would most likely be more efficient.