From Anandtech’s comment section:
The RTX 4090 is rated at 292/330 fp16 TFLOPS (base/boost; non-sparse) @ 450W. The Tenstorrent n300s is rated at 131 fp16 TFLOPS @ 300W and sells for $1400. Both have 24 GB of on-board GDDR6.
So, it’s not really competitive, but then I guess the silicon dates back to 2021 and matched up pretty well against the RTX 3090. The main reason to go with Tenstorrent is probably as a development vehicle, in preparation for their future chips.