It's so cheap to use a SaaS auth provider like Auth0 or Clerk.dev that you might as well implement one of them. It should take less than a day.
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Of course, many established companies offer SSO, ability to login using Google, Apple, other oauth.
I asked around to my test users and a few potential users and they mentioned email is fine. In my own experience as a SWE I used many softwares at work which used just email login. However, many more offered a bunch more.
Will it be fine to open it up to broader audience without all these things?