Probably one of the most well developed open source projects I've seen, both from core contributors finding a way to get paid for what they do every day with nabu casa as well as a large and thriving community.
Over the past two years there's been a ton of work put into making things more plug and play and GUI for folks, but all the technical wiring under the boards is still there for doing just about anything you want.
I have basically everything off the cloud, except for a few things I want on there. If you want everything off the cloud you'd be wise to do a bit of research and get a zigbee and or zwave stick.
Don't blame HASS for IoT providers that are routinely pushing up firmware that breaks anything that interfaces with their products without going through their cloud, but for most things there are things out there that work great without it.