It is a great thing that you are doing with your Dad. As others have said there might be various ways you can be involved in his learning and projects that you both would enjoy. While finding him some in person classes would be good but maybe difficult depending on his location, this forum is filled with helpful people so if he doesn’t want to directly post his questions perhaps you could do that for him.
I get that someone might not have a lot of math skills or math interest, and might not have an immediate interest in software but would still like to learn about circuits. Truth is that circuits can go somewhat deep into math - but with just some basic math Ohm’s Law can open a pretty big vista - something to keep in mind. Net, net: Learning Ohm’s Law is something that should be encouraged and it can be done in a fun way with just a breadboard, wire, resistors, and LEDs, and a power supply plus a pencil and paper, calculator, or spreadsheet.
As for pure hardware learning platforms, Radio Shack used to make kits. They can be found on eBay - just need to try to find one that might still have all or nearly all the parts and a manual (or a pdf copy).
https://www.ebay.com/itm/395651610568?As good as the RS kits were there might be an easier and possibly better intro kit:
https://www.amazon.com/Snap-Circuits-SC-300-Electronics-Exploration/dp/B0000683A4/ref=sr_1_5?The Snap Circuits might seem kid-like but a circuit is a circuit and without the high temperatures, fumes, and safety considerations of soldering circuits these kits can be built with a power supply/battery and the snap-on components in a way that will help show the functions of passive components and some active devices in various circuits; and then with a simple multimeter your Dad can measure voltage, resistance, and current. Such a kit plus your encouragement and guidance might get your Dad on a path where next steps might become more clear.
Along the way if you and your Dad can just frame questions Google, Youtube, and this forum can provide answers. Also, as suggested above W2AEW is a wonderful teacher - if he has a youtube video on a topic that interests your Dad it will be worth watching.
Keep us posted on how it goes. Hope your Dad is asking for an oscilloscope soon
