I’d create a Column called tempcheckbox, format it as checkbox and set formula as (If importedcheck=“Y”, true, False)
Then I’d create another column called checkbox and copy paste the entire tempcheckbox column into it. Then I could delete the other two columns.
For people it depends - Copy pasting the entire column will work only if the user name is the same as the person name format. Else you might have to do some formula work similar to above to be able to copy and paste.