For previous donation platforms operating at same scale on AWS we use Serverless Framework and have our own lambda wrapper which wraps the code and provides monitoring, etc...

For this we just wrote straight up Node JS and plumbing through to Stripe, super simple really. Deployed via github actions on RTE's cloudflare account, really simple. No one time charges from the Stripe side or anywhere really. Only other cost was Sentry, which was more than the hosting as we used it for a lot of the informational alongside error logging.

We have a separate article en-route with all the technicals, just waiting on client sign off, as is stats heavy...