Start at https://iot.mozilla.org
Free download of an image for RPi (recommend 3 or 4) that you can flash onto a uSD card using Balena Etcher. (I’m in the middle of flashing hundreds of cards to be given away at workshops, to make it easier for people to obtain privacy for their smart home installation.)
Would be great to see Balena highlight this as a “featured project” on the Balena Etcher app.
And secondly, would be great for other Balena DIY tutorial projects such as the bluetooth/RPi speakers, and digital photo frame, to be updated to become “web things”, connected to the home network so they can be managed as part of a private and interoperable smart home.