If you look through the Tech Spec pages for each you'll see there are significant differences, they're not equal. The MPB is brighter, better quality built-in mics, touch bar, touch ID sensor, etc.
But if you compare the upper-end Air with the standard M1 12" MBP, yes, they both are based on the same M1 chip, which is the low end of the Apple Silicon chips you'll be seeing coming out. There will be more advanced "M" chips coming to the 16" MBP and desktop models over the next year.
So very similar, but not 100% the same. And we're comparing the lowest end of the Mac lineup.
I am seriously thinking to get the Mac Mini.
I plan to use it strickly with FC and AE / Motion.
I use all external drives.
I am assuming that 512 Go should be good. 16Go RAM.
I also have a mid-2017 iMac. Will be used with my Affinity apps.
I think I can use one keyboard for both from what I have read.
Has anyone worked with one keyboard with two computers? Is it fairly straightforward,
I believe Sidecar will also work.
You will need a KVM switch to use one wired keyboard with two computers. It can be done with a Bluetooth keyboard but would need to disable Bluetooth on one computer and enable it on the other before use. Bluetooth devices can only be used on one device at a time.
I use a single KVM switch between 4 computers and another two more between two computers each and things work well.
One thing also to consider is screen sharing. I use a tiny app called ScreenSharingMenulet between all computers on the network when I don't wan't to go to the other computers or when pulling up the screen from a different remote computer to display on the wall mount TV when dealing with a client at the fromt.