Streaming PipeReader content to Json in ASP.NET MVC - json

Question

We have an ASP.NET MVC application in which we need to send back json response. The content for sending this json response is coming from a PipeReader.
The approach we have taken is to read all the contents from the PipeReader using ReadAsync and convert the byte array to a string and write it as base64 string.
Here is the code sample:
List<byte> bytes = new List<byte>();
try
{
while (true)
{
ReadResult result = await reader.ReadAsync();
ReadOnlySequence<byte> buffer = result.Buffer;
bytes.AddRange(buffer.ToArray());
reader.AdvanceTo(buffer.End);
if (result.IsCompleted)
{
break;
}
}
}
finally
{
await reader.CompleteAsync();
}
byte[] byteArray = bytes.ToArray();
var base64str = Convert.ToBase64String(byteArray);
We have written a JsonConverter which does the conversion to json. The JsonConverter has a reference to the Utf8JsonWriter instance and we write using the WriteString method on the Utf8JsonWriter.
The above approach requires us to read the entire content in memory from the pipereader and then write to the Utf8JsonWriter.
Instead we want to read a sequence of bytes from the pipereader, convert to utf8 and write it immediately. We do not want to convert the entire content in memory before writing.
Is that even feasible ? I don't know if we can do utf8 conversion in chunk instead of doing it all in one go.
The main reason for this is that the content coming from PipeReader can be large and so we want to do some kind of streaming instead of converting to string in memory and then write to the Json output.