I will be completely honest. This is a much bigger challenge than I first thought. Especially with kids that are so tuned into their electronics and getting immediate information or graphics from their media. Keeping them engaged is going to take a couple of techniques that I hope you will find helpful.
First, make sure to schedule a time for this reading. This is crucial because the kids will turn this into a battle between reading and their electronics if you have not agreed on a time and place to have some reading time. For example, bed time is at 9 pm, so you say, "ok, today before bed we're gonna brush our teeth and get ready for bed and then read a book together." This will set up an expectation that they will turn off electronics and get ready for bed, but then there will be another activity together before sleep.
Second, pick a book that will capture their attention. For my kids, up until the age of 5 or 6, they preferred books that had pictures. The more colorful the better. If you have a bedtime book that is specifically 5-minute stories, even better. They will be drawn to the pictures the entire time and it will definitely help to keep their attention. If they are older, I noticed stories with cliffhangers or chapters work better. They have an unbelievable memory and will remember where the story left off from the day before. This may even motivate them to hurry up by brushing their teeth just to get to bed to hear the rest of the story. It makes me smile just thinking about it. Either way, make sure you pick a book or series of books that will peek their interest.
Third, as with everything Dad's do, your example speaks the loudest. Sit with them and read a little before asking them to take over. When they need help pronouncing a letter or word, you are there to pronounce it. They would sometimes look at my mouth to see how I pronounced something, so just be aware of how intensely they are watching you lol. It's extremely simple but very powerful to know that doing something with them is the absolute best teaching tool you have. As a small final note, if you see they are struggling to get through a page, I suggest taking turns from page to page in order to help draw attention to the story. Otherwise, they will be more focused on how they are struggling rather than what is going on in the book.
I highly recommend you add to your arsenal a teaching aid such as the one below to help with the phonetics of reading. It's an inexpensive e-book series and will be an absolute savior between you and the kids.