Depends what you mean with "setting up auth". Once you get into enterprise scenarios, where you need SSO for SSH, Git, your public website, internal tools, ability to revoke accesses, handle trusted mobile devices (ie generating QR codes for VPN/Wireguard access), handling 2FA, etc, etc, it takes more than a week. For such scenarios, doing it yourself and doing it correctly becomes immensely difficult.

Agreed. Done right it's a huge time suck.

I’m building a MVP to show off and validate some ideas. I’m using Firebase and set up auth with my react app in about 10 minutes. I’d never spend a week on auth for a MVP.

I was talking about rolling you own email/password auth from scratch. I keep hearing about Firebase and how easy it is. Is that like AWS Cognito? Does it have custom branding or is it a drop-in form? Can it be hooked to your own SQL database?

It's far easier than AWS Cognito. Yes, I've used both.

Firebase auth is as easy as it gets for auth. Want Username/Pass? Just enable it. Want Google, Twitter, Firebase, Apple, Github, etc.? Just enable it, and write the handlers.

Want to hook into your own SQL database? Easy. Set up a firebase listener, that handles the auth event, and write whatever you want (username, auth details) to SQL.

This is a 100% solved problem and Firebase does a superb job it it.

Awesome, this is great to know. I'll have to consider it for my next side project. Unfortunately I just finished rolling my own, so... :)