Wow and welcome back Jack! I know first hand how much work kidlettes can be and three's a handful for sure. Happy to hear you're back and looking to innovate on something. In that regard, my $0.02 is maybe look to Escape Room gadgets. Escape Rooms are all the rage now and there are tons of options for electronic, electro-mechanical and even purely mechanical gadgets possible to enhance the escape room experience. So a site dedicated to those things could be fun, interesting and leverage lots of your skills in hardware and software design and development.
I bring this up as I've been trying to get some robotics education in our local school system and tried teaching basic robotics. I've seen the basics of circuit theory, basic component understanding(resistors, switches, LEDs, relays, etc) missing because everything taught is usually just assembly instructions. So I tried starting with those basics before getting into building anything and the kids just yawned and lost interest. ie it was like another class and they didn't want that. I'm reinventing the project as an adventure story along the lines of Turing Tumble and 30 Days Lost in Space. My twist is that it's more story/adventure and the repairs/projects will fit the story and quickly build upon and require previous project inclusions ala escape room techniques. I'm basing the parts on one of the many Arduino project kits already on the market in hopes that the students will purchase them for themselves or we can do fundraising such that they can take home kits. I'm building a custom Linux distribution to help with the story and might even add some native software development using Firmata firmware. Still a work in progress but hoping it sparks interest again.
Also wanted to let you know that the https certificates aren't working for the forum URL, https://forum.gadgetfactory.net and had to go http://
Looking forward to hearing what you come up with for reinventing The Gadget Factory and welcome back!
Doug