upgrade to a pricing plan that is not self-served

[ShiD]

hi, I am building an app with several pricing tiers and plans. one of the plans is our Pro plan, which is more expensive and is not self-served (users have to contact us to upgrade to this plan). I wanted to get more information about how this flow can be supported.

I see it was done by others - https://apps.shopify.com/zipifypages?surface_detail=trending-apps&surface_inter_position=1&surface_i...

many thanks!