From what I've seen online Pampers size 8 diapers are just slightly larger than Pampers size 7 diapers.
So far I haven't seen Pampers size 8 diapers in any stores around her or online for sale to the USA so I guess Pampers size 8 diapers are not available yet in the USA.
Right now Pampers size 8 diapers are mostly sold in the UK but maybe they will eventually be marketed and sold in the USA.
I can see Pampers size 8 diapers being useful for older kids who cannot be potty trained or who have incontinence issues.
Pampers diapers are good quality absorbent diapers so it would be good if they continued to make larger size diapers in their current designs without the use of actual baby prints for older kids.
What I mean is to keep the quality of the Pampers diaper such as with Pampers cruisers with extra absorb channels and make them bigger without the prints for older kids and teens who are special needs, disabled or incontinent.
The medical diapers you buy such as medical youth diapers don't work as good as Pampers do.