I would also love to hear any feedback, questions, or concerns about my idea that you have.
Are you aware of
https://coinb.in/? It's client-side web wallet which have similarity with your app, although it's aimed for technical/power user.
If the website goes down, the code is open source and runs locally. So the user can clone the repo and continue on their way.
Could you share link to the source code? I checked both
https://www.giftmonero.app/ and
https://www.giftbitcoin.app/, but didn't find any word "source", "code" or "git" or icon which represent Git/source code.