I wasn’t reasoning, I was just wondering if this had come up before. You’re right though.
It has.
In 1833, the U.S. Supreme Court held that the entire Bill of Rights applied only to the federal government, not to the states. Barron v. Baltimore, 32 U.S. 243 (1833). But after the 14th Amendment was ratified, a series of Supreme Court decisions held that most (but not quite all) of the Bill of Rights now also applied to the states.
The Establishment Clause was held applicable to the States in Everson v. Board of Education, 330 U.S. 1 (1947). The Second Amendment's right to keep and bear arms was held applicable to the states in McDonald v. Chicago, 561 U.S. 3025 (2010).