Thank you for reaching out.
Yes, as mentioned in the thread linked, in order to initiate the process for becoming service provider for Azure Express Route Service, you need to create a Support request with us first with Service Type ExpressRoute Service Provider
I understand you have already reached out to us on the Az community DL, I have replied to your email requesting additional information.
Thank you!
Please "Accept the answer" if the information helped you. This will help us and others in the community as well.