I love the concept and general flow of things. The landing page looks a bit to SaaS for me though, I‘d focus more on design and „feeling“. Otherwise, why is this application better than just generating an invitation using ChatGPT and sending it over WhatsApp?

Also if you want to focus on kids, I‘d make the overall design more playful & colorful, right now it’s all very dark.

Wish you the best of luck with your project!

Disclaimer: I‘m the creator of a similar digital invitation website (invitivo.com).