Yah, boys. (I have a boy). Your son is not unusual.
They have less "patience" to just sit down and read a book for minutes on end. Versus, my daughter, would even at 1 years old, just sit with me, even for an hour, to read books. Versus, boys are very kinesthetic.
Anyway, with my son, especially at only 2 years old, I knew he wouldn't just sit with me, like my daughter would, and "read" a book.
So I didn't go that route with him.
I just verbally taught him words.
Or, both my kids have dry-erase boards... and they LOVE it. So I'd write words on it, and just put it near where the kids play, and they vicariously "learn" it. Inadvertently. I didn't push it. And they could scribble on it too.
Sure, coloring books are fun. But again, my son's attention, at 2 years old, was only like 30 seconds. And then he'd scamper off.
I taught my kids, LOTS of words/vocabulary, just by verbally telling it to them. Even while driving in the car and via chatting.
At 2 years old, I taught my daughter the word "compromise." She loved that word, and it was the biggest word she knew at that time. I taught her this word, just verbally... while we were outside in the yard, playing. For example.
At 2 years old, workbooks or flash cards, are not real spot on. Meaning, at that age, they probably won't just sit there, doing it, nor for very long. Unless the child, like my daughter, would sit there. My daughter had great patience and stamina, at that age for being AT a book.