Hi @Doc2DocLending,
Thanks for your questions! Happy to answer 
1. So we actually do support sensitive data fields via our APIs. You can find more info on sensitive data API functionality here: https://developers.hubspot.com/docs/api/sensitive-data. I suppose you might have a specific use case that isn’t supported, but if any of the functionality outlined in that article doesn’t work on your end, I would suggest taking this up with our support team.
2. Also in this case, we do support using sensitive data with non-HubSpot forms as noted in the KBA here. We also support using the form submissions authenticated API. So I’m not sure why this wouldn’t be working on your end, unless you may have a specific use case.
Regardless, please take this up with our support team or reach out to your CSM as we would love to get a better understanding of your use case and how we can help.
Thank you!