OP: Is there a reason you need more than 32GB of Unified Memory ?
Is there a specific app that requires that much more memory?
Have you tried a 16GB machine to see what this new M1 does ?
I have a base 8GB UM M1 Mini and it does NOT need any more UM ("RAM").
My 8GB Unified Memory runs circles around any Intel Mini with double or triple or quadruple the "RAM" and does it with coldness (no fan spin ups).
At work I use a 2020 Mini CTO / BTO with 6 core i7, 10GBe upgrade, and 64GB of RAM - runs hot as a pistol (needs a cooling fan), system fan ramps up constantly, and apps start to delay opening.
So crazy as it is, still can't match the performance of the base (8GB) M1 Mini.
I think the UM is not the same as DDR memory - Apple's UM runs more efficiently than traditional PC / Intel based DDR memory.
Can't compare Apples to Apples in this case as the Intel based RAM is an "orange".