is it possible to obtain raw data from e.g. the accelerometer on the FLX1s?

MediaTek SoC, and all IIO devices are ADCs (analog-to-digital converters). You can find it in the devicetree here: "/sys/firmware/devicetree/base/gyro/". When you want to get the raw data you can use a dbus channel like in this example :

import dbus
import time

bus = dbus.SystemBus()
sensor_service = bus.get_object('com.nokia.SensorService', '/SensorManager/gyroscopesensor')
gyro_interface = dbus.Interface(sensor_service, 'local.GyroscopeSensor')
props_interface = dbus.Interface(sensor_service, 'org.freedesktop.DBus.Properties')

gyro_interface.start(0)

print("Reading gyroscope data... (Press Ctrl+C to stop)")

try:
while True:
value = props_interface.Get('local.GyroscopeSensor', 'value')
timestamp, x, y, z = value
x_rounded = round(x)
y_rounded = round(y)
z_rounded = round(z)
print(f"Gyro - X: {x_rounded:8.2f}, Y: {y_rounded:8.2f}, Z: {z_rounded:8.2f} mdps", end='\r')
time.sleep(0.1)
except KeyboardInterrupt:
print("\nStopping...")
gyro_interface.stop(0)

The interface looks like this:

gdbus introspect --system --dest com.nokia.SensorService --object-path /SensorManager/gyroscopesensor
node /SensorManager/gyroscopesensor {
  interface local.GyroscopeSensor {
    methods:
      isValid(out b arg_0);
      errorString(out s arg_0);
      description(out s arg_0);
      id(out s arg_0);
      interval(out u arg_0);
      standbyOverride(out b arg_0);
      bufferInterval(out u arg_0);
      bufferSize(out u arg_0);
      type(out s arg_0);
      start(in  i sessionId);
      stop(in  i sessionId);
      setInterval(in  i sessionId,
                  in  i interval_ms);
      setDataRate(in  i sessionId,
                  in  d dataRate_Hz);
      @org.qtproject.QtDBus.QtTypeName.Out0("QList<DataRange>")
      getAvailableIntervals(out a(ddd) arg_0);
      setDefaultInterval(in  i sessionId,
                         out b arg_0);
      setStandbyOverride(in  i sessionId,
                         in  b value,
                         out b arg_0);
      setDownsampling(in  i sessionId,
                      in  b value);
      setBufferInterval(in  i sessionId,
                        in  u interval_ms);
      setBufferSize(in  i sessionId,
                    in  u value);
      @org.qtproject.QtDBus.QtTypeName.Out0("QList<std::pair<uint,uint>>")
      getAvailableBufferIntervals(out a(uu) arg_0);
      @org.qtproject.QtDBus.QtTypeName.Out0("QList<std::pair<uint,uint>>")
      getAvailableBufferSizes(out a(uu) arg_0);
      @org.qtproject.QtDBus.QtTypeName.Out0("QList<DataRange>")
      getAvailableDataRanges(out a(ddd) arg_0);
      @org.qtproject.QtDBus.QtTypeName.Out0("DataRange")
      getCurrentDataRange(out (ddd) arg_0);
      @org.qtproject.QtDBus.QtTypeName.In1("DataRange")
      requestDataRange(in  i sessionId,
                       in  (ddd) range);
      removeDataRangeRequest(in  i sessionId);
      setDataRangeIndex(in  i sessionId,
                        in  i rangeIndex,
                        out b arg_0);
      hwBuffering(out b arg_0);
      @org.qtproject.QtDBus.QtTypeName.Out0("XYZ")
      value(out (tddd) arg_0);
    signals:
      propertyChanged(s name);
      @org.qtproject.QtDBus.QtTypeName.Out0("XYZ")
      dataAvailable((tddd) data);
    properties:
      readonly b isValid = true;
      readonly s errorString = '';
      readonly s description = 'x, y, and z axes angular velocity in mdps';
      readonly s id = 'gyroscopesensor';
      readonly u interval = 80;
      readonly b standbyOverride = false;
      readonly u bufferInterval = 0;
      readonly u bufferSize = 0;
      readonly s type = 'GyroscopeSensorChannel';
      readonly i errorCodeInt = 0;
      readonly b hwBuffering = false;
      @org.qtproject.QtDBus.QtTypeName("XYZ")
      readonly (tddd) value = (0, 0.0, 0.0, 0.0);
  };
  interface org.freedesktop.DBus.Properties {
    methods:
      Get(in  s interface_name,
          in  s property_name,
          out v value);
      Set(in  s interface_name,
          in  s property_name,
          in  v value);
      @org.qtproject.QtDBus.QtTypeName.Out0("QVariantMap")
      GetAll(in  s interface_name,
             out a{sv} values);
    signals:
      @org.qtproject.QtDBus.QtTypeName.Out1("QVariantMap")
      PropertiesChanged(s interface_name,
                        a{sv} changed_properties,
                        as invalidated_properties);
    properties:
  };
  interface org.freedesktop.DBus.Introspectable {
    methods:
      Introspect(out s xml_data);
    signals:
    properties:
  };
  interface org.freedesktop.DBus.Peer {
    methods:
      Ping();
      GetMachineId(out s machine_uuid);
    signals:
    properties:
  };
};

Good luck !