I know this is shitty and that it is not working.

Dart serial read with linux commands.dart

import 'dart:async';
import 'dart:convert';
import 'dart:io';

class Serial2IO {
  // Default: ttyUSB0
  static final String _serialPort = "/dev/ttyUSB2";

  // Request serial data via Linux commands... yeah...
  static Future<Map<String, dynamic>?> request(
      Map<String, dynamic> data) async {
    // Configure serial port
    var pr = await Process.run(
      "stty",
      ["-F", _serialPort, "57600", "raw"],
    );

    if (pr.exitCode != 0) {
      return null;
    }

    pr = await Process.run(
      "bash",
      ["-c", "echo '${jsonEncode(data)}' > $_serialPort"],
    );

    if (pr.exitCode != 0) {
      return null;
    }

    bool finished = false;
    Map<String, dynamic>? json;

    Process p = await Process.start("cat", ["/dev/ttyUSB0"]);

    p.stdout.listen((event) {
      String rawjs = utf8.decode(event);
      print(rawjs);

      if (rawjs.length < 10) {
        return;
      }

      Map<String, dynamic> tmpJson = jsonDecode(rawjs);

      if (tmpJson["status"] == null) {
        return;
      }

      if (tmpJson["status"] == "ok") {
        json = tmpJson;
      }

      finished = true;
    });

    while (!finished) {
      await Future.delayed(Duration(milliseconds: 100));
    }

    p.kill();

    return json;
  }
}