GNU Stow is a tool that helps manage symlinks. It is very similar to dotstree - arguably dotstree is closer to stow than other dotfiles managers. The main differences are:
If you were using stow, instead of a spec.yaml you would create a stowrc file in each program's folder. To my knowledge, stow doesn't traverse a directory tree looking for all stowrc files, so you would have to run it separately for each program. Of course you could automate that with shell scripts. Incidentally, you could also automate it with dotstree: Your install command would invoke stow and your check command would invoke stow -v -n.
Stow can do more advanced tricks with symlinks than dotstree, and gives you more fine grained control over how various situations are handled. For managing dotfiles, I didn't find these useful, so dotstree has less customization and is simpler.
Stow also doesn't support handling install scripts, and lastly stow is written in Perl while dotstree is in Python -- something which may or may not be important to you.