Some people commented that my previously proposed solution to instantly show/hide the Dock in Big Sur is not working on their new M1 based Apple Silicon Macs.
I was able to investigate and provide a working solution, tested on a M1 MacBook Pro:
defaults write com.apple.dock autohide-delay -float 0 && defaults write com.apple.dock autohide-time-modifier -float 0.4 && killall Dock
For doing the same on Intel-based Macs, check out to the full post on how to remove the delay in showing / hiding the Dock in macOS Big Sur.
Thanks a lot. It works for me.