By the reviews, and the way the RAM is installed and integrated onto the motherboard (SOC) it would appear that Apple is enhancing via multiple methods, the effectiveness of the amount of RAM available. Thus, 16 GB may act more like twice that because they have optimized how it is used across the system.
The M1 is more efficient in many ways, including, maybe, RAM usage, but there's zero evidence for the "16GB on M1 = 32GB on Intel" claim, and it has been debunked
ad nauseum in other threads.
In a lot of cases, testers haven't actually checked to see if memory is even an issue - either on the M1 or the Intel Mac they are comparing it with - and apparently didn't get the memo that MacOS will mop up any unused RAM to use as file cache etc: you have to look at things like memory
pressure to see if lack of RAM is causing a bottleneck. See also the threads on excessive swap use on M1 Macs, which could
partly be down to relying on swapping rather than having adequate RAM.
However, thing is, you really shouldn't get more than 16GB of RAM (especially at Apple prices) without doing a bit of research as to whether you actually
need that much - even on an Intel machine. 16GB always has gone a long way - but the people who need more, need more.
...and of course, what we
haven't seen yet is what a 32 or 64GB Apple Silicon chip can do on those tasks where RAM is an issue... Your Mini may be hosing the 2019 iMac at the moment - but when newer machines come out it could be getting sand kicked in its face again... Now, normally, you might say "yes, there's
always something better coming out in a few months' time" but right now we
know that Apple have only released what is going to be the "low end" range of Apple Silicon Macs.