What options should you have available on sign up for a SaaS MVP?

I personally, don't risk connecting my signups to my socials unless it's something specific for that social. Because I might forget my social account password, or it gets banned, or all the other issues that may occur.

The only SSO sign up I use is with Google. Otherwise I prefer email

I prefer using "Sign in with Google" or receiving a magic link instead of relying on usernames and passwords. The latter is always my last and least preferred option.