The new silicon oxide batteries

First developed over 20 years ago. Not exactly new.

claimed

Yea, in a laboratory setting. Replacing graphite anodes with silicon is problematic for consumer products due to the massive volumetric changes when lithiated and its high reactivity. So let’s say they found a way to mitigate these drawbacks and applied this to an EV. It may look better of paper, but it won’t match the cycle lifespan of an NCM based cell. Lifespan is already a massive concern for EVs considering their price and unknown depreciation curves.

They have been developed and will start entering the market in the next few years.

I’ll believe it when I see it.

Solid state batteries exist but are too expensive at the moment.

SSB just means the liquid or gel electrolyte between the anode and cathode has been replaced with a solid conductor. It’s not some magical thing that’s super hard to achieve like fusion. The point is to address the issue of thermal instability in over current situations when your electrolyte would tend to vaporize and burn when the cell ruptures. It does that nicely but brings its own set of headaches to the table, like grain boundary resistances and low charge instability. There’s no free lunch and any “new” thing is going to have its own set of drawbacks.

battery technologies will improve a lot over the next few years

Why do people believe this? The time vs. $/kWh curve has been flattening out exponentially the last few years. Battery companies are pouring billions into R&D, and we’re only seeing slight incremental improvements in the capability of the technology as every facet of production is optimized.
There is nothing to support this blind faith that some new battery chemistry will be the savior of the BEVs.