If you’re already using one of the major providers (GMail, Outlook365, etc.), there isn’t much to configure; you go to Mail Accounts, click your provider like Google or Microsoft, and login on their website to authenticate.
https://www.fastmail.com/blog/push-email-now-available-in-io...
Unfortunately it doesn’t sync properly with Gmail. I am in the process of de-googling my life so that’s okay with me. I use mail.app with my fastmail account and it’s perfect.
People here are discussing email apps, not Gmail apps.
Gmail apps only work with 1 provider (gmail), while email apps works with all email providers.
I might be an anomaly. I've ran iPhones before and have an iCloud email address presumably, but have only ever used the Gmail app for email on my iOS devices. And on my other machines I just use the web app. This seems to be the same for most people I've worked with in the last 5 years or so. Obviously it's super anecdotal and just from observation.