I just uploaded (to experimental) a package policy-rcd-declarative, which ships a policy-rc.d script that can be configured through static files, in an attempt to address some of the issues pointed out in this bug report.
It's not yet ready for prime time (hence the upload to experimental rather than unstable, given the short time before the buster release), but comments are definitely welcome. -- To the thief who stole my anti-depressants: I hope you're happy -- seen somewhere on the Internet on a photo of a billboard