FURTHER UPDATE: Trying to re-invoke a previously invoked line in Windows command line I accidentally copy-pasted
C:\Users\Andi\work\g\lovr\build-apk>%ANDROID_HOME%\cmake\3.22.1\bin\cmake.exe
into the command line, which if you think about it attempted to invoke the current directory as a command, failed, printed nothing to stdout, redirected that nothing to the path to cmake.exe, and truncated cmake.exe to be a 0-length file which now obviously can't be executed