That's really interesting, I took a quick look through your links. I have the same ultrasonic sensor but haven't gotten to play with it yet- trying to get other things to work first. Which wifi outlet did you use? That is one thing I do have plans to use but haven't gotten around to yet. Also, Node Red looks like a home automation kit I ran across being sold. I was tempted to get their kit (can't recall the site selling it) because it looked so easy to use, expand, and customize.
I've been trying to get my existing stuff to work before adding more things to my to do list. I think I sorted most of the issues to getting the pins/ gpio#s correctly. From now on the 'pinout' command will see a lot of use. I still can't help but search around and seeing all the sensors and gadgets available for the Pi. The latest thing I got working is a radar motion sensor. The PIR sensor worked well, but the so called radar sensor senses 360 degrees and really does sense through doors and walls. I can see that making a pretty effective intruder detector. I still have to try to see how it works through an outside wall from the inside. Another 'if I ever get to it project' is to use one of those outside to trigger a security camera. If it works as I hope I can use it to trigger a security camera. Now there are a lot of false triggers from car headlights and other things I don't care about. The camera has connections for external triggers, and the sensor is pretty small and can work from inside a plastic case which will make it possible to close it into a weatherproof box. Although I haven't tried, I believe the microwaves can be focused to exclude areas by shielding with aluminum foil. So many projects, so little time.
I also need to look into the various models of Pi. I have two Pi3b+s now but using smaller, cheaper, less power hungry versions will be a plus in many uses. I now see many things don't need all the features of the 3b+. I believe a reduced size, 1 USB2 port version was recently released.
Probably my first standalone working project will be used to monitor temperature, humidity, motion controlled lights, water leak detector, and CO in the basement. I currently have a really old X10 setup automating the lights there, and I am surprised it is still working after all these years. Another thing I've purpously avoided for now is getting the Pi to wireless connect with something- except the internet for updates etc. I have a standalone LAN with a NAS connected that I can eventually experiment with.
Anyway, thanks for the links, I will have to look at them more closely. I still want to use Python and learn it better- one of the reasons I started using the Pi, but in the mean time it looks like Node Red can get some projects off the drawing board.