Local-only octoprint is feeling better and better.
Not all smart plugs are proprietary. You could even make one yourself with an ESP-01, a relay, and open-source firmware like ESP Home if you know what you’re doing to make it safe at that kind of voltage. If you’re overconfident in your ability to make it safe, then you’ve still got an untrustworthy smart plug at the end of the process, so it’s not necessarily a good idea, but it’s not proprietary.
Hmm that’s a good point. Never seen one for sale that I trusted though, and I did have a good look at one point.