So far as far as rumours go and thanks to the Nvidia leaks, the most legit rumours that we have are from Kopite who has successfully leaked many Nvidia GPUs in the past such as Ampere's lineup a year prior to release.
Based on my findings, here is what we know and obviously take it with heaps of salt.
It's funny. What I said about "the new Switch SoC"?
— kopite7kimi (@kopite7kimi) March 2, 2022
1. T239 ✔️
2. Black Knight/Dane Whitman ❌ (Tim Drake is also start from D.) ???
3. AD10F/based on Ada Lovelace ❌ (GA10F)
4. SEC8N/the same as Orin ❓
5. 1024FP32/half of Orin ❓
So what that means is that the Switch 2's SoC should be called T239 based on GA10F which is Ampere using Samsung's 8nm. It could have 1024 Cuda cores. Theoretically this would make sense assuming the Switch 2 launches in 2024sh because the original Switch was based on Maxwell that launched during Nvidia's Pascal era, Switch 2 would be based on Ampere and launch during Nvidia's Lovelace era. T239 is a customized version of T234:
This is a preliminary picture of T234 in Wikipedia. Very clear.
— kopite7kimi (@kopite7kimi) June 11, 2021
So why do we always guess?
Nintendo will use a customized one, T239. pic.twitter.com/Qp5Im5udlQ
Assuming that it's all true, we still don't know what further customization Nintendo will require for it such as will it have Tensor cores? RT cores? Clock Speed? CPU? etc. It's highly unlikely it will have 12 core CPU so similar to his thoughts of halving the cuda cores, halving the CPUs would make sense.
It should be on par or beat the Steam Decks performance so at the very least, it will be around the power level of a PS4 but at 720p. With DLSS and maybe Ray Tracing (Since Steam Deck has RT support), it could exceed it but they would want to keep the cost down.
I think $300 is doable but $400 would be worst case.
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850