It is OK for parents to make their older kids wear diapers and they should wear them and use the diaper instead of using the toilet.
Especially if the older kid has wetting problems or wets the bed they should wear diapers all the time to keep them dry.
That is very good if your 8 year old son does not want to be potty trained.
I would not want to be potty trained either if I were your 8 year old son and would prefer to wear diapers which are healthier than using a toilet and also diapers are more comfortable than underwear or boxer shorts.
Yes you should send your 8 year old son to school in a diaper so he does not have to use the school toilets and can concentrate on his school work more.
You should let your 8 year old son go back to wearing diapers full time and not be potty trained.
Also you should do the diaper changing and make him wear just a diaper and shirt around the house.
The best diapers for an 8 year old boy that wets a lot would be Pampers Baby Dry size 7 or Pampers Swaddlers size 8.
Another very absorbent diaper that would fit an 8 year old boy that wets a lot is Dollar General Gentle Steps size 7 diapers.
They swell up a lot and hold a lot of pee and even myself as an adult wear them with a bit of modification and they are very squishy and get bulky once you fill them up with pee.
It is normal for your 8 year old son to poop his diaper at school everyday.
Pooping a diaper in school or anytime is better than pooping in the toilet and walking around and sitting in a poopy diaper feels awesome as well
Tell your son to enjoy his diapers which you said he does and don't feel ashamed about it.
If your 8 year old son wants to go back to diapers you should let him.
Your 8 year old son should be able to fit into a Pampers Baby dry size 7 or pampers Cruisers size 7.
There's also a size 8 Pampers swaddlers or even Gentle Steps size 7 diapers that would fit your 8 year old son.
Diapers are the most comfortable underwear and you can pee and poop in them without having to go to the toilet.
I wish my parents would've put me back in diapers at 8 or at least never potty trained me.
I loved wearing diapers at 8 years old but had to sneak wearing them.
Here's another boy of around 8 years old that was made to wear diapers by his parents .