Consumer grade cards are strictly forbidden in data center environments due to Nvidia license agreement. But there are even US companies that will sell you eight 4090s in a 4U box with all cooling shrouds removed in place of liquid cooling.
I thought 4090s didn't support NVLink. How does it help to put 8 of them in a box?
You can simply break up the workload and let each work independently on its part.
Many workloads are very well suited for this. You only need NVLink if you need the cards to collaborate on the same (sub-)task.