SOLVED:

Actually collaborated with upwork freelancer Vladimir on this, workaround is to take a look a storagePath where images are uploaded, and then extract list of publicURLs from there, and return array of strings:

// Automatic FlutterFlow imports\nimport '/backend/supabase/supabase.dart';\nimport '/flutter_flow/flutter_flow_theme.dart';\nimport '/flutter_flow/flutter_flow_util.dart';\nimport '/custom_code/actions/index.dart'; // Imports other custom actions\nimport '/flutter_flow/custom_functions.dart'; // Imports custom functions\nimport 'package:flutter/material.dart';\n// Begin custom action code\n// DO NOT REMOVE OR MODIFY THE CODE ABOVE!\n\n// Set your action name, define your arguments and return parameter,\n// and then add the boilerplate code using the green button on the right!\nimport 'dart:io';\nimport 'package:path/path.dart' as path;\nimport 'package:image_picker/image_picker.dart';\nimport 'package:supabase/supabase.dart'; // Add Supabase import\n\n//final picker = ImagePicker();\n// Initialize Supabase client\nfinal supabase = SupabaseClient('supabaseURL',\n    'supabaseAPIKEY');\n\nFuture<List<String>> getUploadedImages(String storagePath) async {\n  final List<FileObject> files =\n      await supabase.storage.from('userBucket').list(path: storagePath);\n\n  final publicUrls = await processFiles(storagePath, files);\n\n  return publicUrls;\n}\n\nFuture<List<String>> processFiles(\n    String storagePath, List<FileObject> files) async {\n  List<String> results = [];\n\n  await Future.forEach(files, (FileObject file) async {\n    // Perform asynchronous operation for each item\n    final fileName = file.name;\n    results.add(await getPublicUrl('$storagePath/$fileName'));\n  });\n\n  return results;\n}\n\nFuture<String> getPublicUrl(String fileName) async {\n  // Simulate an asynchronous operation\n  final publicUrl =\n      await supabase.storage.from('userBucket').getPublicUrl(fileName);\n  return publicUrl;\n}

Supabase Storage / Public URLs / Connecting Storage and Table