If your aim is to create a list of widgets (assuming both your lists will have same number of elements). You can try

List<Widget> getWidgets() {  List<Widget> my_widget_list = [];  const _categoryNames = <String>[    'Length',    'Area',    'Volume',  ]; const _baseColors = <Color>[    Colors.teal,    Colors.orange,    Colors.pinkAccent,  ];  for (int i = 0; i <= _categoryNames.length -1 ; i++){    my_widget_list.add(MyWidget(_categoryNames[i],_baseColors[i]));  }  return my_widget_list;  }Widget MyWidget(String categoryName, Color baseColor){  return Container(    color: baseColor,    child: Text(categoryName,));}

There is a zip function from package:quiver. Combined with collection-for (Dart's equivalent to Python list comprehensions) can get you most of the way there. Dart does not have Python's automatic unpacking, so unfortunately you won't get nice variable names:

my_widget_list = [  for (var pair in zip([_categoryNames, _baseColors]))    MyWidget(pair[0], pair[1]),]

"Pythonic" Dart Syntax

You can do something that looks very similar to Python using Control Flow Collections.

    List<Widget> myWidgetList = [      for (String name in categoryNames)        for (Color color in baseColors)          if (baseColors.indexOf(color) == categoryNames.indexOf(name))            myWidget(name, color)    ];

Maybe a little less "Pythonic" but more concise . . .

    List<Widget> myWidgetList = [      for (String name in categoryNames)        myWidget(name, baseColors[categoryNames.indexOf(name)])    ];

Specifically, you should read over Control Flow Collections: Composing

Complete Unit Test

For you convenience here is a quick unit-test you can run.

import 'dart:core';import 'package:flutter/material.dart';import 'package:flutter_test/flutter_test.dart';void main() {  test('build list of widgets with composing', () {    List<Widget> myWidgetList = [      for (String name in categoryNames)        for (Color color in baseColors)          if (baseColors.indexOf(color) == categoryNames.indexOf(name))            myWidget(name, color)    ];    List<Widget> myOtherWidgetList = [      for (String name in categoryNames)        myWidget(name, baseColors[categoryNames.indexOf(name)])    ];    expect(myWidgetList.length, equals(myOtherWidgetList.length));    expect(myWidgetList.toString(), equals(myOtherWidgetList.toString()));    print(myWidgetList);  });}const categoryNames = <String>[  'Length',  'Area',  'Volume',];const baseColors = <Color>[  Colors.teal,  Colors.orange,  Colors.pinkAccent,];Widget myWidget(String categoryName, Color baseColor) {  return Container(      color: baseColor,      child: Text(        categoryName,      ));}