what I've done with my kids, I have many. 5 is a bit young for electronics in my experince, their motor skills are still developing and are just learning to hold tools in their hand / pens pencils.
I've gotten a lot of ads for electronic kits and I usually spend more time reading the directions and figuring it out than doing the actual project. I've done the ELEGOO kit from Amazon and that was a lot of fun. made lights blink, fans blow etc.
-so many kits from LEGO! when you are doing building with the instructions you can modify what you built to do other things. this I think is the best way to go
-start easy with replacing batteries in things. show them it doesn't work without batteries, then put in batteries and it works. show them different types of batteries.
-take apart toys / fix toys. when something breaks, figure out why it breaks. it is usually a wire that needs to be soldered. that is really fun.
-if you have something like power wheels for really little kids, you can get an upgrade kit to increase the power, that is REALLY fun.
-get a rasp-pi kit from cana and build a retro pi. show them what USB ports are and how to plug things into USB. show them the parts of the computer.
-rip apart a cable and show them what is inside.
-show them how to pair a Bluetooth speaker / headphones.
-introduce them to a proper mouse and keyboard and how to use it. gaming is a great way to do this, especially roblox/minecraft.
The best possible thing you can do is anytime something breaks in your house is to help them fix it and be patient with them. be very patient and don't do it for them no matter what. show them how to do it, undo it and let them do it. last week I got some RFID stickers and showed them how to program a message with their iPad. they scan the Ipad and it says their name, or sends Mom/Dad a message. very fun! good luck!