This message is mostly for debugging and monitoring. But hey, the generator is at least loading, so; yay, I guess?

The counts read:

handled {X} of {Y} enabled call-sites ({A} unsupported API, {B} skipped due to diagnostics) …

• enabled call-sites: every Dapper call-site where Dapper.AOT is enabled ([DapperAot]), whether or not it could be handled - so Y = X + A + B, and 100% means what it says;
• unsupported API: calls to Dapper APIs that Dapper.AOT does not (yet) implement, for example QueryMultiple or the multi-map Query overloads; these stay on vanilla Dapper;
• skipped due to diagnostics: calls Dapper.AOT understands but declines, for a reason reported as a separate diagnostic (for example DAP016/DAP017/DAP050); these also stay on vanilla Dapper.

Note that “handled” is a build-time statement: the call is intercepted and compiles. Whether it behaves identically is what your tests are for.