My (now sidelined/back burnered) startup's main product was kind of like an advanced IFTTT that runs on your own hardware. The major difficulty was scaling up development and production without capital, and getting a basically Turing-complete system to be easy to use.
While I would love a "self hosted" IFTTT, the biggest issue to me would be getting the integrations.
IFTTT is the ONLY thing on Google home right now that lets you create fully custom voice actions. It's got a lot of things like this.
There are a few similar services, but at the end of the day, if it's within my capability to talk directly to a service, I'm going to just write my own code to talk to it (or my FOSS HA system will more likely support it very quickly).
IFTTT's power to me is completely in its ability to integrate with otherwise "locked down" services.
