Hi,
We are in a similar situation. I am also building in IC a platform that is web2 for the MVP. My project will transition into web3 and I think that having the IC backend will help when we go to that phase of the project.
- My backend is in rust, and I think i have figured out the DB migrations and the Stable memory.
- For auth I have integrated web3auth with firebase
- For payments, I am still checking options but I was thinking of Stripe. Did you do any research in the topic?