You can. PowerShell already has a 15-year precedent of signed scripts - you generate a signature and embed it in the script in a specific way, and the shell can

You can. PowerShell already has a 15-year precedent of signed scripts - you generate a signature and embed it in the script in a specific way, and the shell can be configured to only run scripts if their signature is valid. (PowerShell script signing is based on standard Windows codesigning certificates, but of course this hypothetical bash script signature verifier can use GPG keys instead.)