What’s the point on the email category (iOS and macOS)

I'm not entirely sure I follow. You should be able to search and find the information you've stored in 1Password regardless of what category it is in.

To do this you’ll have to open 1PW. But you can’t do this within apps or in the web.

Not only for webmail but also for the apps?
There is no mechanism on macOS for filling such information into non-web browser apps at present.

Sorry it seems I’ve posted my question into the wrong category. Can you please move this to the iOS category?

You can also drag and drop from 1Password into Spark, but as I say there isn't any way we could fill this information automatically with the technology currently available.

I‘ll guess you mean macOS but I‘m talking about iOS and iPadOS.
@MacOS: At the moment I‘m out of reach of my Mac but I remember that Big Sur has an option for filling apps. But maybe I’m wrong here.

@iOS: I could access 1PW within apps that require an password. However I only can switch between vaults but can’t look into the mail category.