How is it possible to upload iOS builds to App Store Connect by using Xcode Cloud and App Store Connect API Key instead of Apple ID?

Guys, do you happen to know how it is possible to upload iOS builds to App Store Connect by using Xcode Cloud and App Store Connect API Key instead of Apple ID?

We want to upload iOS builds for our clients, but some of them have Individual type of accounts, so we were used to ask them for their login and pass (Apple ID) so we can log in and create all the developer certificates prior to build upload.

But now we want to remove this step from the work flow by uploading builds to their accounts by using their App Store Connect API Key instead. They would connect to their account in our website, then we'll be able to handle everything from then on, hopefully?