@Leschkeb This is how I would approach your flow. Tip: Remember to rename your actions to keep your flow organized.
Manual Trigger
While you are building and testing your flow, use a Manual Trigger. It's a lot easier to run tests and build your flow without having to leave Power Automate. MS Form Response ID's are sequential, select your Form ID and input a number into the Response ID field.

SubTask Matrix
You'll need a way to store a matrix of sorts for your subtasks. Although you can set this in the flow, I'd recommend using a SP list or an Excel table. Doing it this way will make it easier for you to update your subtasks at a later date.
I've created a very simple subtask table in Excel. One column for the subtask name, another for the category and one for a unique ID. The ID needs to be a number.

It's important that your choice selection must be listed in a column of your Excel table so you can filter on it. It should match your choice option exactly. The column header in your Excel table can't have any spaces.

Get the SubTasks
Using the List Rows Present in a table action, filter out the subtasks by the choice selection. The List Rows Present in a table action will only take a single filter query. Ensure that you insert the dynamic content from your MS Form in between single quotes.

Return a Count of SubTasks
Whenever I use a Filter Query in a List Rows Present in a Table action, I always like to return the count of items returned in a Compose action. This is helpful when building a flow and can also be used to troubleshoot your flow.
Insert a Compose action. Add an Expression. Use the length() function.

Select the Dynamic content tab and insert the body dynamic content from the Filter Array action into the length() function.

Run a test. Review the output of the Compose action and ensure it's returned the correct amount of tasks based on the selection made in your form. In my example, I've selected Single Choice 1.

The output of the Compose action is 3.

Create a Task
Add a Create a Task action and insert the appropriate dynamic content into their respective fields of this action.

Initialize an Array Variable
Initialize an Array variable in the root of the flow.

Loop through Each SubTask
Add an Apply to Each action to loop through each subtask returned from the List Rows Present in a Table action.
Insert an Append to array variable action.

You can copy/paste this array format and replace the blue text with the appropriate dynamic content.
{
"id": "[id dynamic content here]",
"title": "[subtask name dynamic content here]",
"isChecked": false
}
Compose Checklist Array (optional)
This step is optional however it can be helpful for troubleshooting and to ensure that you have collected all your checklist items.
Add a Compose action to store the array variable.

Run a test. Review the outputs.

Add Checklist Items to Planner Task
Add an Update Task Details action. Insert the ID dynamic content from the Create a Task action. In the Checklist section, click on the icon to switch to input entire array.

Insert the array variable into the field.

Run a test. Check planner and review the checklist items.

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You might be interested in this Planner Tutorial: How to Email Attachments 🖇 to Your Planner Tasks
When you add attachments to a Planner task from your computer, the files are automatically saved in the Documents document library of the SharePoint site associated with the M365 Group of your plan. Instead of downloading email attachments to OneDrive or SharePoint just so you can add them to a Planner Task—automate it.
In this Microsoft Power Automate Tutorial—I’m going to show you how build a flow that will take your email attachments and add them to a Planner task. All you need to do is copy a link to a task, forward the email to yourself and the attachments will be saved onto SharePoint and attached to your planner task. Stay tuned till the end of the video where I’ll show you how to use Trigger Conditions so this automation only runs when specific conditions are met!
IN THIS VIDEO:
✅ How to get the Message ID from an Email
✅ How to use the Get an Email (V2) action with a Manual Trigger
✅ How to use the split() function to split an email subject line
✅ How to use the Scope action to group your actions
✅ How to create a folder for email attachments on SharePoint
✅ How to use the Get Attachment (V2) action
✅ How to create attachment files in SharePoint
✅ How to use the Append to Array variable action to collect attachments
✅ How to add multiple attachments to a Planner Task
✅ How to switch a manual trigger to an automated trigger
✅ How to use Trigger Conditions in a when a New Email Arrives Trigger
✅ How to trigger your flow when only specific emails arrive
Hope this helps!
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