The current market saturation of recycling isn’t the amount of a panel that can be recycled.
The current market for nuclear reprocessing isn’t the amount reprocessable either. But to adhere to your argument, it’s the probability for a given panel to be recycled; if there isn’t an economic rationale, because recycled materials from panels is more expensive than vergin materials, then it’s called being out of market, not market saturation.
In reality we aren’t recycling solar panels.
No reactor has ever prodiced the same material it ran on
This happen routinely even in non breeder reactors, industrial nuclear nuclear reprocessing is a thing and many reactors in the world run on MOX fuel with plutonium extracted from spent LWR fuel. You only need a breeding ratio higher than 1 because otherwise fissile content will keep diminishing. Arguably there’s no more base research needed, both breeding and nuclear reprocessing are time tested process. What we need is industrial scale up, which is a little bit further than a proof of concept