I get it OP. Burn out is a real risk for PDA kids.
I wouldn't write off state schools. But I wouldn't rush to put him in one either. He needs a low pressure environment with people who understand him.
If that needs to be home ed for now then so be it.
You are a good Mum to be considering all the options.
I'm coming to the end of my home ed journey with a kid with a similar profile. He'll be starting at a SEN unit within a mainstream secondary next term. Had I failed to get him in, we'd have home ed right the way through to GCSEs.
My advice:
I've not found online classes much use for younger kids. If you want to dip your toe in OutSchool has a very wide selection of classes in all sorts of subjects. £2 tution Hub has less choice but is cheaper and very ND friendly.
Try out a few stand alone classes or a short course and see if the format works for him. I wouldn't sign him up for an Online School at his age.
I've found apps a good fit. They can be dipped into as much or as little as your kid can handle. They add a little structures learning without being overwhelming.
We did Reading Eggs and Maths Seeds when he was little. Moving on to Night Zookeeper for creative writing and SpAG.
BBC Bitesize has some good free maths games.
At 5, an hour, maybe 2, per day on the 3 Rs should be enough.
If your kid has special interests, you'll want to leave him plenty of time to pursue them.
Make sure he has plenty of resources to draw on. And make yourself available to help and encourage.
Join your local home ed Facebook group to find friends and playdates. Join the Home Education for All (H.E.F.A) Facebook group for general home ed advice.
It's good his school is pursuing an EHCP. Follow the process even if you home ed. If you want to get him back into school in the future, you'll want all your SEN ducks in a row.
And Good Luck!