From understanding above you might need to think in Azure Apps way rather than Sitecore.
As all the xDB/xConnect logical role are web apps incase of performance and distributed multi region/ Geo distributed application/environments can be setup by
And for deployment you might can use this
The performance hit isn't in the documentation because it depends on a myriad of factors. The key thing to understand here is latency. There are various ways of mitigating this latency however. You can have xConnect Collection role services in each region and use xConnect Scalable Reads combining them with Azure SQL Auto Failover Group capabilities.
I will ...