Laptop Zen 3 is already equal in multicore perf to the M1 for the same wattage IIRC. While being on 7nm still. Don't underestimate AMD.
Mac mini uses like 25-27w at the wall. 15-25w TDP for the 5800u doesn't include RAM (it's LPDDR4 at 1.1v will use a lot more power than M1 LPDDR4x at 0.6v). 5800u also has a chipset that consumes a few watts.
5800u has some features that the M1 does not (these would likely increase M1 power usage), but still doesn't seem close in power consumption.
4800u isn’t that different as far as power goes (mostly different in performance). A mini-PC with it uses almost 70 watts under load.
https://www.anandtech.com/show/16236/asrock-4x4-box4800u-ren...