Tricky problem you have here.
I’ve tried the example app since that was the first solution that came to our mind to. But in another place we had others do that for us. As in we had an App marketplace where our customers could share their projects which they had built using the SDK. And some Apps that we had built in-house to made available to customers not part of the product but the marketplace. If that is not an option, but the SDK is already out there being used. Reaching out to users and ask if you can use their project in your testing might be an option.
In another company we had internal tools that were built using the SDK, so we had natural testing of the SDK.
In all of them making early access version of the SDK available to people was very helpful in ironing out kinks in the SDK.