Outlook Tasks export to a web based collaboration tool possible?

I have a client with 11,000 tasks in Outlook that is sharing them with approx 10 users to delegate tasks

This is proving unreliable so I wanted to get them into using Planner in 365 but from what Ive read its still not possible 2 years after Microsoft announced it was going to be able to do so

The client wont have time to create the Tasks again so I was wondering if there is any web based collaboration tools out there that can import Tasks in Outlook?