I got M1 macOS, so confirmed if Appium worked on the environment.
With Xcode 12.2 environment, only simulator did not work because of build architecture issue on M1 macOS. Real devices connected to the M1 machine had no issue. These were expected result for us. Probably we can fix the issue tweaking build architecture on M1 macOS.
Xcode 12.3 RC had an issue https://github.com/appium/WebDriverAgent/issues/432 , but it was more general issue.
appium-mac2-driver and Appium Desktop worked on the M1 env. Yey, good news.
[update] Btw, https://github.com/Carthage/Carthage/pull/3071 might help for this issue.
[update] Appium 1.20 works well.
~ my tech diary ~ 