just tried it, it seems floats which "look" like an integer indeed get interpreted as such; e.g. an index:

{
  "name": "test",
  "fields": [
    {
      "name": ".*",
      "type": "auto"
    }
  ],
  "enable_nested_fields": true
}

when submitting documents:

[
  {
    "bar": 100.0
  },
  {
    "baz": {
      "foo": 123.0
    },
  }
]

both

bar

and

baz.foo

get created with type

int64