We do support publishers using an API directly, and running none of our code.
Our ad client is also open source, and pretty simple: https://github.com/readthedocs/ethical-ad-client -- we have publishers who use a published version with Subresource Integrity, but you can also just host the JS yourself if you want.
Our ad client is also open source, and pretty simple: https://github.com/readthedocs/ethical-ad-client -- we have publishers who use a published version with Subresource Integrity, but you can also just host the JS yourself if you want.