Without having looked into it… Is ptrace the best / only better alternative? Wondering, might Linux namespaces be (more) capable / suitable as a torsocks version 3?
Other alternatives to consider:
Once upon a time there was torsocks version 1. If I remember right, version 2 was a complete rewrite which came with many improvements. If the current torsocks maintainer agrees, this might become torsocks version 3. That would help getting the tool into Debian, help its popularity and also help getting Whonix to use it.