Yes it’s just you. They released a 2FA app because it complements their existing password manager and because Google has one. Since Proton is positioned as a privacy-first alternative to Google, it makes sense they’d launch competing versions of any given app or program Google does. A 2FA app also wouldn’t capture any kind of personal data.

What could they do better than Aegis, which is already FOSS and privacy preserving?

What could they do better than Tutanota mail, Which is already privacy preserving? By your login Proton shouldn’t exist at all. Is it your opinion that non-privacy respecting software should have lots of competition and options but privacy respecting ones should not? That’s not the greatest idea.