I personally reached the multi-cloud situation a handful of times - it's particularly common if you're doing anything on-prem, or with customers on certain regi

I personally reached the multi-cloud situation a handful of times - it's particularly common if you're doing anything on-prem, or with customers on certain regions (eg China). If you're truly married to AWS/GCP/whatever stack (fargate, lambda, etc), it's literally impossible to migrate. The successful migrations / multi-cloud setups I've seen all used the cloud provider's specific features sparingly (eg S3 encapsulated on a single library, so migrating is simple), etc But I agree if you're doing something simpler, sticking to a single provider is fine