Adults wearing diapers open in public is not considered to be socially acceptable.
This is because diapers are considered to be underwear and we are not supposed to wear just our underwear in public.
Although it's more socially acceptable for babies and toddlers to wear just diapers openly in public but not for adults.
It's seen as cute for toddlers and babies to run around in just their diaper but adults not so much.
However it's not technically illegal to be in public wearing just a diaper or just a diaper, shirt and shoes as the diaper does cover your private areas.
You might get some weird looks or be asked to leave an area but it's not really illegal.
If you do want to wear just a diaper in public just be aware that some people may give you weird looks, may laugh or make fun of you or they may just think you're weird.
The best thing to do if you want to wear diapers outside without pants is to do it in your own yard in a private fenced in area.
Or buy some land in the woods and move away from neighbors where you can roam around in your diapers.
I want to do this myself as I love wearing just diapers outside and wish it were more socially acceptable to do so in public but for now I do so in my backyard that is privacy fenced in.
I even go on my slide and swing in my backyard wearing just a diaper, shirt and shoes.