Tech made a post recently where they mentioned that they are working on squashing some bugs related to the OS Big Sur version. Beyond that, fZ appears to be working through Rosetta2.
Big Sur has made a number of under the hood changes where undoubtedly some of those will conflict with previous code. Once those are squashed, Look to Rosetta2 first.
If you are looking for a native version, prior to that post, they did note that they could compile their code over with little issues, many of the components that they rely on have not been compiled over. Without these components, there is little sense.
Think ACIS. The engine that is used for smooth modeling. Or, the Rendering engine LightWorks (though, I personally doubt this one will ever be ported for reasons outside of ADS' control.)
Off the top of my head, I can't think of others, but as with most development these days, there are multiple dependencies. All or most of those dependencies will need to be compiled over too. How long that will take, it is anybody's guess.
That being said, these bare-bones base models appear to be pretty damn impressive. While I do think there is a bit of hyperbole both with Apples marketing and with pundits, if one takes into account the market segment they belong in, they are impressive. One can hope that this is enough to shake those dependency devs into action if they consider what is potentially coming down the pipeline.