Following Can user accounts be managed via the command line?, I did:
sudo dscl localhost -create /Local/Default/Users/myuid
Then following How to login as a different bash user in terminal?, I did:
sudo -s -u myuid
but only get:
sudo: unknown user myuid
Then I checked Fast User Switching in System Settings, and found that the
"Show in Control Center" is greyed out and cannot be selected