Hi. I'm Brian and I'll try to help.
If you're setting up a computer for an organization or another person, NEVER use your own address as the username. Create a new one. You should reset the computer to factory settings or perform a clean install of Windows so that nothing of yours is left on the computer. If you wanted to allow them to use your subscriptions or software, that's probably not legal. They need their own licenses.
While I don't know if it's still possible, there has been a way to bypass the need for an Internet connection when starting with a fresh install. See if this page helps: https://www.adamsdesk.com/posts/windows-11-install-without-internet/. I believe this page is safe to reference.