I checked the Azure Pricing Calculator just now.
Pricing for services in the EU GDPR "Sovereign" safe-zones (e.g. "Germany Central (Sovereign)") is largely the same as for services in other zones:
Azure App Service in Germany Sovereign: $62/mo
Azure App Service in West US: $54/mo
1TB Azure Storage in Germany Sovereign: $21.00
1TB Azure Storage in West US: $20.80/mo
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As for reliability, I haven't noticed any difference in availability and downtime between my Azure resources in any of the zones I've got services in. YMMV. Lately Azure's actually looking pretty good compared to AWS's spate of outages over the past 6 months.