For others looking for a self-hosted alternative like Formspree I wrote something similar that deploys to AWS Lambda [0]. Nothing fancy, just a AWS Lambda endpoint that uses SES to send emails. Instead of aliasing email addresses for privacy like OP I just use the native Node.js crypto module to create a hex string of the address upfront.
Thanks, also a big TypeForm fan. For the future, there's also a variety of other similar form forwarding services like this if you don't want to run your own. Like Formspree (https://formspree.io) for example.
[0] https://github.com/danielireson/formplug-serverless