I will completely second what
@deeveedee says.
It can be a completely production worthy machine. Mine is. It will run dual 4K without any problem. I am running on one 43" 4K monitor and don't see why it wouldn't do dual screen. I ran sidecar with it.
Getting an M1 Mac Mini can be very price competitive if... you don't need a lot of storage or RAM. It all depends on what you will be doing with it. Apple's base price is reasonable but not the 16GB RAM and upgraded storage versions. There is no option to go higher than 32GB and I am running with 64GB RAM and 3TB of NVME SSDs for a total net cost of <$1000. Something to keep in mind.
And yes... TimeMachine works fine. I backup and restore mine that way from machine to machine. Actually really everything that I can think of works so far with the Bluetooth accommodation of the watch unlock having been the last thing I had to fix.