You're better off with a single card, like intel arc pro b70 with 32 gigabytes of VRAM unless you need something external. You're going to lose quite a bit of performance over thunderbolt. However, Nvidia still is king for its ecosystem.
If you could get 2x 16GB eGPU in external cases for $1398 vs the Intel B70 for $1199 to $1299 (MicroCenter pricing), some would choose the ease of use of getting the Nvidia solution up and running, over the lower price. Personally I'm rooting for Intel to be stronger in the GPU department.
you could have 2 to get 32GB VRAM, which is enough to run a decent AI model locally.