As I mentioned in my earlier post about the drawbacks with the entity-attribute-value data model used in Firebase Analytics and Google Analytics app plus web, it is hard to know what events and associated attributes and data types are logged without proper documentation. Another way to get an overview is to actually query the table. Below you find an example of how to do it.

SELECT 
  event_name, 
  ARRAY_AGG(struct(name, value)) as attribute FROM(
  SELECT 
    event_name, 
    param.key as name, 
    CASE
      WHEN param.value.string_value is not null THEN "string"
      WHEN param.value.int_value is not null THEN "int"
      WHEN param.value.double_value is not null THEN "double"
      WHEN param.value.float_value is not null THEN "float"
    END as value
    FROM `<project>.<dataset>.events_20190902`, UNNEST(event_params) as param
    GROUP BY event_name, name, value)
  GROUP BY event_name
  ORDER BY event_name asc

That would return something like below (in JSON format)

[
  {
    "event_name": "app_clear_data",
    "attribute": [
      {
        "name": "firebase_event_origin",
        "value": "string"
      }
    ]
  },
  {
    "event_name": "app_remove",
    "attribute": [
      {
        "name": "engaged_session_event",
        "value": "int"
      },
      {
        "name": "ga_session_id",
        "value": "int"
      },
      {
        "name": "firebase_event_origin",
        "value": "string"
      },
      {
        "name": "ga_session_number",
        "value": "int"
      }
    ]
  },
  {
    "event_name": "app_update",
    "attribute": [
      {
        "name": "engaged_session_event",
        "value": "int"
      },
      {
        "name": "previous_app_version",
        "value": "string"
      },
      {
        "name": "firebase_event_origin",
        "value": "string"
      },
      {
        "name": "ga_session_number",
        "value": "int"
      },
      {
        "name": "firebase_screen_id",
        "value": "int"
      },
      {
        "name": "ga_session_id",
        "value": "int"
      },
      {
        "name": "firebase_screen_class",
        "value": "string"
      }
    ]
  }
]

Hope this helps.