Someone on Dutch site Tweakers.net did a napkin calculation regarding the performance:
(Translated from Dutch)
"The GPU should deliver 6x the performance of a Steam Deck. A Steam Deck does ~1,638 FP32 TFLOPs of RDNA 2.0.
6 times 1,638 equals 9,828 TFLOPs. Of course, there are also other RDNA 2.0 consoles on the market: the PS5 and the Xbox Series. Because they all use the same architecture, you can compare the TFLOPs (which equates to (clock speed × shading units × 2)/1,000,000) fairly well. However, some games prefer more cores, while others perform better with higher clocks.
Xbox Series S: 4.01 TFLOPs
Xbox Series X: 12.15 TFLOPs
PS5: 10.29 TFLOPs
PS5 Pro: 18.05 TFLOPs
Steam Deck: 1.64 TFLOPs
Steam Machine 2026: 6x Steam Deck
The hardware will use RDNA 3.0. Clock for clock, RDNA 3.0 performs about 8% better than RDNA 2.0. So if it were exactly 6x the GPU performance of a Steam Deck, it would amount to about 18.2 TFLOPs of RDNA 3.0 (9.1 × 2 because, starting with RDNA 30, AMD is doing the same trick as Nvidia; integer shaders can theoretically be used for floating point).
We know the clock speed will be 2.450 MHz, so we can calculate the system's shading units based on the calculated TFLOPs (taking this with a grain of salt).
9.1 × 1,000,000 / 2 / 2450 = 1857. This isn't a common number, of course. The closest estimate is 1792. AMD always increments 256 times, so it will either be an RDNA 3.0 GPU with 1792 shading units or 2048.
If it's 1792 units, it amounts to 17.56 TFLOPs (RDNA 3.0); if it's 2048, it's 20.07 TFLOPs. RDNA 3.0’s performance at 20.07 TFLOPS puts it on par with the relative floating point performance of an RX 7600M XT, GTX 1080 Ti, RTX 3060 12GB, and Arc A770. At 17.56 TFLOPs, performance is comparable to an RX 7600M, RX 6600, RTX 2060 Super, and Arc A560."
And Digital Foundry: