Is there a way to scroll the Settings screen and Apple Mail screen - with assistive technology?

Voice Control provides several commands to scroll the messages list in Mail. By default, saying "Scroll down" or "Scroll up" will scroll all lists showing on the screen by one page. If numbers are showing on the items in the list, as they are in your screenshots, and you want to scroll just one of the lists, say commands like "Pan up at 16" or "Pan down at 8" to perform a half-swipe gesture at the numbered item. If you want to scroll a bit more each time, say "Swipe up at 12" or "Swipe down at 6". You can also scroll left and right as well. For more commands, search the Voice Control commands for "scroll" and "swipe" at Settings > Accessibility > Voice Control > Customize Commands.

This support page may be helpful:

Accessibility - Mobility - Apple

It may also be worthwhile to directly contact Apple Support - and ask to speak with an Accessibility Specialist. Apple have a team dedicated to offering support for accessibility issues. They will be able to offer help and support with suggestions and specific settings for users with difficulties with motor function and other disabilities.

You can contact Apple Support using the Contact Support link at top-right of this page. Alternatively, you can initiate contact, or open a support case, using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/gb/app/apple-support/id1130498044

I hope this information is helpful in obtaining the specialist help that you need.