...and some more simple command line utilities. I've code signed all executables and binary libraries I could find. This has got rid of most errors already.
Now I'm struggling with the "hardened runtime" requirements. I understand I can somehow add entitlements - but have no clue how to do that, and what to add. Somewhere there was reference to PCRE - I don't think Perl uses that itself, but certainly does deal with regexes a lot. How would I add eg. the JIT entitlement (if that was required)? Most documents refer to .mobileprovision files or similar - but I'm dealing with a desktop application.
And as all of this is rather non-standard, we don't use Xcode at all. So I wouldn't even know how to use Xcode to create a profile for an an app which is managed completely "outside" of a normal macOS development environment.