Can this approve a Microsoft sign-in notification?

No. Push approval is a proprietary exchange between the app and Microsoft’s servers, not something a browser page can perform. This produces standard TOTP codes only. Many Microsoft accounts can fall back to a verification code, and that is the part this covers.

Does it work with work or school accounts?

Only where the account accepts a standard authenticator code. If your organisation requires Microsoft Authenticator specifically, or enforces push approval through Entra policy, no third-party tool can satisfy that.

Is the code format the same?

Yes for standard TOTP: six digits on a 30-second step, SHA-1, as specified in RFC 6238. Any service issuing different parameters passes them along in the otpauth:// link, and you can set them by hand under Advanced.

Microsoft Authenticator Alternative — Generate TOTP Codes in a Browser

Microsoft Authenticator does two separate jobs: passwordless push approvals for Microsoft accounts, and ordinary TOTP codes for everything else. Only the second of those is a standard anyone can implement — and it is the one this page reproduces.

Where Microsoft Authenticator is the better tool

Push approval for Microsoft and Entra accounts is smoother than typing digits, and number matching resists approval fatigue.
Cloud backup restores your tokens to a new phone without re-enrolling each account.
It is often the only accepted second factor in an organisation that enforces Entra policy, so it is not optional in that setting.

Worth saying plainly

Gen2FA is not a replacement for Microsoft Authenticator. It holds nothing you have not pasted in, it lives in one browser, and anything you save here is stored in readable form. Keep an authenticator app enrolled and keep your recovery codes. This is the route in when the app is out of reach.

Where it leaves you stuck

Mobile only. There is no desktop client, so a laptop login still means picking up a phone.
Push approvals only work for accounts that support them; everything else falls back to the same 6-digit codes any authenticator produces.
Corporate device policy can wipe or lock the app, taking the tokens on it with them.

When a browser is the right call

You need a code for a non-Microsoft account and the phone is not available.
You are enrolling a service that issues a plain setup key and want to check it works before committing.
You work on a managed laptop that will not let you install anything.
You want a second, independent way to produce a code while you sort out a phone.

Moving a key across

This does not replace push approval for Microsoft accounts. Those stay with the app.
For any account showing a standard 6-digit code, open that service’s 2FA settings and reveal the text key behind the QR image.
Paste it here and compare the result against the app for the same account.
Leave the app enrolled and keep your recovery codes; this is the fallback route, not the vault.

Questions

Can this approve a Microsoft sign-in notification?: No. Push approval is a proprietary exchange between the app and Microsoft’s servers, not something a browser page can perform. This produces standard TOTP codes only. Many Microsoft accounts can fall back to a verification code, and that is the part this covers.
Does it work with work or school accounts?: Only where the account accepts a standard authenticator code. If your organisation requires Microsoft Authenticator specifically, or enforces push approval through Entra policy, no third-party tool can satisfy that.
Is the code format the same?: Yes for standard TOTP: six digits on a 30-second step, SHA-1, as specified in RFC 6238. Any service issuing different parameters passes them along in the otpauth:// link, and you can set them by hand under Advanced.

Microsoft Authenticator in a browser, when the phone is not the answer