I never used ascom vspec, I suppose it uses the variable rate setting capability of eqmod mounts (maybe other mounts?). You may do the same in indi at the telescope class level (this is not limited to indi-eqmod). The only problem would be to retrieve the worm position between restarts, I don't remember if there is an access to the worm indexer in the skywatcher protocol for instance. And how ascom vspec may do that.
Concerning guiding software I am totally ignorant.