To override Big Sur's Gatekeeper restriction: "cannot be opened because the developer cannot be verified" from the command line
Example with MongoDB (can be run against a folder e.g., JavaSDK or individual executables):
xattr -d com.apple.quarantine /Users/me/Downloads/mongodb-macos-x86_64-enterprise-4.4.2/bin/*
This appears to be sticky for all identical versions of that executable, i.e., if you have two copies of the identical binary in unrelated directories, removing quarantine for one seems to enter a file signature hash into the allowed list globally.