Is there a way to create a task list using voice prompts??
You could just use Siri to “make a note in Drafts,” for each thought/task that comes to mind. Then when back using Drafts itself, select the individual drafts you’d like to have in the list from the side panel, click on “Operations,” then “merge,” from the options.
Alternatively, sticking with speech, if in Drafts and using the “dictate,” function it’s possible to use the “new line,” voice prompt to do just that. E.g., “Task one new line Task two,” would return…
Task one
Task two
Either way, you’ve now got a single list of tasks which you could, say, send to a task manager via an appropriate action. Alternatively, if you just want to use the simple list format within Drafts (clickable checkbox), select all lines, then run this action to convert to a checklist.
I’m not clear on what is meant by “voice prompts” and what flavour of task list, so I’ll make a few suggestions.
If you are in a draft and dictating lines of tasks and want to add the simple task check box convention to a line, you might try something like this:
“open square bracket space bar close square bracket space ba apple new line open square bracket space bar close square bracket space bar banana”
This should give you the following when you insert into your draft.
[ ] apple
[ ] banana
Because the text is just being captured and handed over to Drafts, there’s no context for it to automatically know that you probably want to keep prefixing checkboxes as it does when you are entering text directly into a draft.
However, all of the square bracket space bar stuff is slow and a mouthful so in this situation I’d personally dictate it as lines and then get an action to prefix each line with the check box characters as @TDK_SA90 has above 
All of the above could be equally applied to a bullet list or a Taskpaper list. It is just a case of including the characters you want to use.
Now, if you are wanting a running list where you ask Siri to occasionally add an item, my first question would be why not just use the built in reminders app and create a list in there for capturing these things? Drafts may be a Swiss Army knife for text capture, but if you already know it is going to be a list item and you need to use Siri to add it, it should be the most efficient path to add it directly to the reminder.
e.g. “Hey Siri, add apple to fruit list” could be used to add “apple” to the reminders list called “fruit”.
If you really do need the list in Drafts, then Drafts has an option under settings to synchronise with a Reminders list. So you can use the above sort of phrasing to add it to a particular list.
Why not just add it directly to Drafts via Siri though? I’m glad you asked. The reminders import template allows you to specify tags for the imported draft. I don’t think direct capture to Drafts for this is possible currently. But if you have a particular tag applied, then as @TDK_SA90 suggests you could merge notes, but in this case because they share a common tag, you could do this programmatically by adding all of the tagged entries to a ‘master’ draft and of course the action could add in check marks, archive/remove completed items, etc.
Hope that helps.
I use Todoist. It has direct support for Siri. However, you have to pronounce “Todoist,” in such a convoluted/unnatural way (I have no interest in a Tattooist Siri), that by contrast, saying “take a note in Drafts,” is a lot more reliable.
I used to use the Reminders list > Drafts as mentioned by @slyumer prior to Drafts 5 gaining the ability to interact with Siri directly.
Thanks for all the information, it will be fun playing with it…
exactly the same experience for me too! I just assume that my northern UK accent is not favored by most voice assistants.