Requiring high throughput and in order delivery is not really a sweet spot for most cloud integration services, they are built to hyper-scale and fall down fairly quickly when order matters. “Functions as a service” or event Event Hubs would display these attributes. Would like to know more about what the back end services are, but without this info a common pattern would be to use something like DataBricks to normalize the data for the target platforms and do the insert. If you are looking to homogenize your on-prem and in cloud solution to this problem, that this or Swen’s K8s solution might be overkill.
If this solution stays fully Windows/Azure then in years past I have used IIS/WAS with WCF to integrate Solace into Windows Applications, this can provide things like autoscaling with order. Probably better/more portable solutions in the .Net.Core or .Net.Framework might be worth looking at.