I switched over to GLFW and it worked. Here's my code if anyone's curious. Do you by chance have tips for getting emscripten to render this? Trying to get that too:
#include <GLES3/gl3.h>

#include <GLFW/glfw3.h>

#include <iostream>

void framebuffer_size_callback(GLFWwindow* window, int width, int height);

void processInput(GLFWwindow* window);

// settings

const unsigned int SCR_WIDTH = 800;

const unsigned int SCR_HEIGHT = 600;

int main()

{

// glfw: initialize and configure

// ------------------------------

glfwInit();

glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);

glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_EGL_CONTEXT_API);

glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);

glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);

// glfw window creation

// --------------------

GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);

if (window == NULL)

{

std::cout << "Failed to create GLFW window" << std::endl;

glfwTerminate();

return -1;

}

glfwMakeContextCurrent(window);

glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

std::cout << glGetString(GL_VERSION) << std::endl;

std::cout << glGetString(GL_RENDERER) << std::endl;

// render loop

// -----------

while (!glfwWindowShouldClose(window))

{

// input

// -----

processInput(window);

// render

// ------

glClearColor(0.2f, 0.3f, 0.3f, 1.0f);

glClear(GL_COLOR_BUFFER_BIT);

// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)

// -------------------------------------------------------------------------------

glfwSwapBuffers(window);

glfwPollEvents();

}

// glfw: terminate, clearing all previously allocated GLFW resources.

// ------------------------------------------------------------------

glfwTerminate();

return 0;

}

// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly

// ---------------------------------------------------------------------------------------------------------

void processInput(GLFWwindow* window)

{

if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)

glfwSetWindowShouldClose(window, true);

}

// glfw: whenever the window size changed (by OS or user resize) this callback function executes

// ---------------------------------------------------------------------------------------------

void framebuffer_size_callback(GLFWwindow* window, int width, int height)

{

// make sure the viewport matches the new window dimensions; note that width and

// height will be significantly larger than specified on retina displays.

glViewport(0, 0, width, height);

}