I have an early reader. His friends all went to school this year, and he's still at nursery because of his autumn birthday. Best friend is August born, so it hit him hard when they all left. He's been there since 5 months old because I was in post and had no mat leave.
To say he's bored now is an understatement.
So we taught him to read like his friend (who thankfully still comes for after school care a few days a week in his big boy uniform with his book bag and weekly take home book)
You asked for what other parents have done, and while I agree with them you don't need to worry, that wasn't your question. And I'm sure someone will flame me for this.
Here's what we have done so far in our house.
ABC posters up- we had a standard one with Aa Bb Cc so we could teach ABCs and their sounds but we could switch over to lowercase quickly. We then bought one that has letter pairs. Making it visible and normal something you talk about and refer to.
Made it tactile- DP had 3D printed a bunch of letters with some leftover filament. You could use card or paper. What seemed to make it click for him was DOG DIG PIG. He had learned to spell both dog and pig, but I wasn't sure it was sounds or memory. By laying letters out and asking him to change one letter to make the words (how do you change dog to dig) and making it really fun, that worked well. I would have him change one letter and keep going
Pig
Pin
Bin
Ban
Bat
Cat
Car
Far
Fat
Can you make it fast
We also had a Magnadoodle and would write on there and make silly pictures. Or I'd do fill in the blank. (_ark) He loved shark dark park and that was when I introduced letter pairs.
Switch it up- for a while he was less keen on me pointing at a word and more on spelling it himself in his head so I might ask how to spell something like mom or dad. This was good because we could then be out and see something and spell it and we could talk about it. We would do this kind of thing all the time. The other day he spelled spoon and fork.
Captions- We l have them on all the time now and he's been following along with his cartoons. He's reading out the title of what he wants so I will probably start prompting "ok which Peppa do you want" and having him read it instead of saying "that one." Any opportunity to read something is an opportunity. Same for any signs, posters, menus, whatever that you see around town.
Knowing when to stop- when he's bored or tired we don't push. We don't want it to backfire and him not to like it. While the last few months were a huge adjustment for him, I'm glad he's had this time at home and isn't in school where that isn't an option.
Apps- we only let him do educational apps on the iPad not games or cartoons on it. This means he associates it generally with learning activities. So he can draw, use a skeleton app naming bones (that was a weird phase), or do Duolingo ABC. It is excellent. He unwinds with "The owl" a bit after dinner. He started it a couple months ago before his 4th birthday and recently finished them all (there's something like 700 mini lessons if you can call them that) and restarted it. It's very cute, incremental, positive and not too annoying. Super helpful when flu struck us all one after another over the holiday! He's gotten a few other phonics games for his birthday and when we play them, we remind him that they are just like the owl but it means we can play too. Not everything can throw cartoon confetti!
Watch the hidden sounds- P, B and D do not sound like puh, buh and duh. Be really careful you don't fall into that trap and correct them when they do too. All are like a soft sound of just the letter- this is much easier to say than type, sorry. If you don't, they will try to sound out "bap" buh a puh or "pad" puh a duh. This causes unnecessary confusion
Read together- read all the time. Switch up them reading to you or you reading to them. I don't always want to break a flow because I want him to hear the cadence of language especially if it's written with some rhyming. But if it's not, I might offer to read the full page after he identifies this word. He prefers I read to him but now he might do a few pages of an easier book before he gets bored and again, knowing when to stop
Have a goal- there's something expensive that he wants (a computer) and we said when he can read a big boy book like one of the Roald Dahl's we will get it. He hasn't forgotten.
So much praise- we make him feel like he's the most clever boy who ever lived. He read "you can talk to us" on a flier in the GP waiting room the other day and we sent a picture of it to dad and to his grandparents. Try to make it as positive as possible, not a chore, and something to be proud of.
Good luck!