I would recommend contacting Americans United for Separation of Church and State.
If you check their website, you can see their mission:
Americans United for Separation of Church and State is a nonpartisan
educational and advocacy organization dedicated to advancing the
separation of religion and government as the only way to ensure
freedom of religion, including the right to believe or not believe,
They deal specifically with the issues like yours:
We use high-impact litigation, powerful lobbying and grassroots
advocacy to ensure that:
- Religion does not dictate public policy. The government does not tell Americans what to believe or how to practice their faith.
- Discrimination is not justified under the guise of religion.
There's a page on AU's wbsite for reporting violations of the Establishment Clause: https://www.au.org/get-involved/report-a-violation/form.
You can also get in touch with AU members who live near you: https://www.au.org/get-involved/chapters.
AU is not a government entity (as your question asks), however, they are very knowledgeable about the proper channels for such complaints, and about the nuances of the Establishment Clause of the first amendment.