Use SFPro font in Flutter rather than default SF UI

Question

Flutter's Cupertino Text Theme uses the older versions of Apple's San Francisco Font known as .SF Pro Display and .SF Pro Text. It then adds custom tracking (letter spacing) to a few default styles. https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/cupertino/text_theme.dart

This presumably will only approximate native iOS behaviour and requires each font size to be effectively hard coded with the correct letter spacing values.

There is no official support for the actual SF Pro font that is available from Apple for download. Apple also provides a guide on its tracking values. https://developer.apple.com/design/human-interface-guidelines/foundations/typography/

Is there a way to use the actual SF Pro library and is there a reason why Flutter does not?

For example SF Pro could be presumably be implemented like this

pubspec.yaml

fonts:
    - family: SF-Pro
      fonts:
        - asset: fonts/SF-Pro.ttf

Then the font values could be hard coded:

class SFTextStyles {
  static const _font = 'SF-Pro';

  static const TextStyle body = TextStyle(
    fontFamily: _font,
    fontSize: 17,
    letterSpacing: -0.43,
  );
  static const TextStyle callout = TextStyle(
    fontFamily: _font,
    fontSize: 16,
    letterSpacing: -0.31,
  );
  static const TextStyle caption = TextStyle(
    fontFamily: _font,
    fontSize: 12,
    letterSpacing: 0,
  );
}

or even calculated:

extension SFTextStylesTracking on TextStyle {
  tracking(double fontSize){ 
    return merge(
      TextStyle(letterSpacing: _Tracking[fontSize]);
    }
  }

  // source of values: https://developer.apple.com/design/human-interface-guidelines/foundations/typography/

class _Tracking {
        static const Map<int, double> tracking = {
            6: 0.24,
            7: 0.23,
            8: 0.21,
            9: 0.17,
            10: 0.12,
            11: 0.06,
            12: 0,
            13: -0.08,
        etc..
        }
}

Is there a reason why this is not done / not a good idea?