Thanks a lot this is super helpful, much appreciated.
I was just thinking about the other services, for example would Cloudflare be ok? We proxy all our traffic through them, and they are key for DDOS prevention, I suppose data goes encrypted to them.
To ensure you don't have problem down the line, make sure they themselves store their data in the EU (for exemple, french OVH allows you to chose where you data is stored, their french datacenters are fine, but I would not go with their canadian datacenters).
Allow me to remind you that it's not just the hosting but anything that touches that data, eg analytics and error reporting services are concerned too