This is hard to do, especially in a non-custodial, non-KYC way. OpenNode is beta-testing a plugin that auto-converts fiat payments through Stripe into BTC, so when that's released you could do that with Zaprite. Or right now you could connect a Strike account (if you have one) and then simply buy BTC as soon as the USD lands in your account. We're also exploring connections with Exchanges which will could do this for you automatically.