To answer point 1: Maybe to start out, but in the long run, having only social logins may cause your app to lose a segment of the market (I don't know how much). If you're fine with that, then by all means only support social logins.

However, I strongly suggest having it (or some way for someone not to use a social provider) if you want to have as many users a possible.

Personally, I don't have a google account, I'm wary to use my Apple account for non-Apple sites, and I don't have facebook, instagram, new gen z hotness app, etc... And I can confidently say I am not alone in choosing to use apps which don't require a social login.

At the end of the day though, password auth isn't a non-trivial problem. It is a solved problem of which there are numerous articles/papers and many libraries for most languages/frameworks. For example, the Phoenix framework for Elixir has a built in command which scaffolds auth, and it works really well (I have used it in a personal project): https://hexdocs.pm/phoenix/mix_phx_gen_auth.html. For JS, you can use something like passport: https://www.passportjs.org/packages/passport-local/. If you want a separate service entirely (even though it would be more complex to have a separate service to start out), there is GoTrue: https://github.com/netlify/gotrue. These are just a few suggestions of tech I have come across. There is so much more out there, I encourage you to research options to see what may be a best fit.

If you're worried about password auth, maybe give one time passwords a try. They don't require any password reset flow, and are generally secure when implemented correctly. As an example, I don't have a password for my craigslist account. Every time I want to login, I can choose to get a magic link/otp which gets exchanged for a session. In practice (and this is my personal opinion), I prefer magic links. They are one time, hard to guess (again dependent on implementation), can be time limited, and most likely won't be intercepted in transit (though it could be in a rare circumstance).

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To answer point 2: yes.

If your app is to order things (I use things in a general term) it sounds like eCommerce. And if you're in eCommerce, you better have a way for a user to track what they have ordered and how much they have paid for it at a minimum. Otherwise, your site may come across as a scam, even though it uses Stripe. Sketchy sites can use Stripe to get your money (albeit, it'll be a one time payment).

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In conclusion, auth for your application seems crucial. Email/password auth is still relevant for applications. While not necessary for an MVP, there is a segment of the market you will lose if you don't have an email/password option, or even an email/OTP/magic link option (I don't know how much, really going off an educated guess).

Best of wishes in building your app! I genuinely hope it is successful and safe for people to leverage :)

--- Edit 1: You may not need auth after all.

After thinking a bit more about some UX from different ordering services (i.e. airlines, doordash). Maybe a way to circumvent is to send that order number w/ an order summary via email, which of course you have stored in your db. You may still need to store an email (depending on the complexity of an order number), but it wouldn't require a full on auth solution to start out with.

It would make my points above moot, and may be lowest friction way for you to get your app off the ground while still giving a user the ability to have access to their orders/order history.