That’s very fair and your are absolutely right that it will be very difficult to retrofit old homes. Do you think newer office buildings and schools would be a good place to start?
New builds should be a no-brainer because you can integrate them into the build process, but for existing buildings you'd really have to ask a civil engineer. For example if you're building with gasbeton/AAC it's still going to be a helluva job retrofitting the required ducting through it. But yeah, schools and office buildings would be a good start if you can manage it.