Can I send a JSON object to BigQuery without stringifying it?

I am trying to figure out if there is a way to send a JSON object to a BigQuery table that has a column of type JSON. I know the current practice is to stringify the JSON and send it over which gets parsed and stored as JSON but Im trying to find a way to send an object.

So I know the following works:

type Message struct {
    stuff      int64  `json:"stuff"`
    stuff2     string `json:"stuff2"`
    stuff3     string `json:"stuff3"`
}

stuff3Map := map[string]string{
    "status":        "ok",
    "response_time": "5",
}

stuff3JSON, err := json.Marshal(stuff3Map)
if err != nil {
    log.Fatalf("Failed to marshal stuff: %v", err)
}

msg := Message{
    stuff: 34,
    stuff2: "test",
    stuff3: string(stuff3JSON)
}

However Id like to know if it would be possible to make something like the following work

type Message struct {
    stuff      int64  `json:"stuff"`
    stuff2     string `json:"stuff2"`
    stuff3     map[string]string `json:"stuff3"` // or []byte or string
}

stuff3Map := map[string]string{
    "status":        "ok",
    "response_time": "5",
}

stuff3JSON, err := json.Marshal(stuff3Map)
if err != nil {
    log.Fatalf("Failed to marshal stuff: %v", err)
}

msg := Message{
    stuff: 34,
    stuff2: "test",
    stuff3: stuff3JSON
}

I know that BigQuery does support it (as mentioned here https://docs.cloud.google.com/bigquery/docs/schemas#standard_sql_data_types) and also as mentioned here: https://docs.cloud.google.com/bigquery/docs/schemas#creating_a_JSON_schema_file I can do it by defining a JSON schema but the objects I want to send are not of predetermined structure.

From what I can get from the docs, its a client library issue more than a BigQuery issue but still.

Also this https://docs.cloud.google.com/bigquery/docs/nested-repeated#define_nested_and_repeated_columns exists but also needs predetermined fields.

Finally, the bigquery.JSONValue(mapData) type exists but is that what I need and is there no way without it ? Thank you in advance.