There's just no benefit to using SATA for it. Even a PCIe Gen3 x1 link provides a significantly higher performance - and those aren't exactly rare these days. Why invest a huge amount of time and money into building a controller chip which is significantly worse than its competitors in every way? Even if you're very interested in backwards compatibility it would make more sense to go for PCIe-based U.2 instead. And 3.5" is just a waste: look at 2.5" SATA SSD teardowns, they are mostly empty space.

If you really want a classic hotswap bay form factor, something like the Aoostar WRT Max allows installing a bunch of M.2 SSDs in a 3.5" bay. The QNAP TBS-h574 gives you five swap bays for M.2 SSDs - albeit in a cute custom form factor. Just want a whole bunch of storage? The Asustor Flashstor Gen 2 has up to 12(!) screw-down M.2 slots. At 8TB per slot that's 96TB of storage - significantly more than the 40TB 4-bay NAS you are proposing.

Or wait for someone to build a NAS which accepts EDSFF SSDs. But don't count on it, because there's no market for prosumer-level EDSFF drives (nobody has a bay for it, and M.2 is a far more attractive option for most people), so there's no market for EDSFF-compatible NASes either. Unless you plan on shipping them with M.2-to-EDSFF adapters - but at that point why not save a whole lot of space by going directly for M.2 instead?

It's a bit like asking for a Mini-ITX motherboard with an SP5 socket so you can plug in the latest Epyc CPU, and wanting it to have DDR3 memory slots: even if it's technically possible at all, what market is it supposed to serve?