There is a LOT of technical heavy lifting happening here that makes this a little unacceptable to mortals; I bet we could make a “helper” webpage that allowed people to generate these links easily.
The equivalent of this might be a nifty little project for someone to implement:
import urllib
site = 'meta.discourse.org'
title = '''My special checklist'''
category = 'todo'
tags = ['tag1', 'tag2']
template = '''\
# Important!
Do these things:
[ ] thing one
[ ] thing two
'''
query = urllib.parse.urlencode(dict(
title = title,
category = category,
tags = ','.join(tags),
body = template,
))
print(f'https://{site}/new-topic?{query}')
prints this link