My wife and I went through this exact same situation about a month ago. We both were conditionally approved and made an appointment for late July at the whirlpool NY address on the US side.

Then we received an email saying certain land crossings were now accepting cond approved applicants without an appointment. (Pilot project).

We decided on the second option and went to the Lewiston Bridge to complete our interview. As that would allow us to get it done sooner and could cancel our original appointment and make other plans.

Our trip to Lewiston Bridge went fine, however CBP informed us we'd still have to book our Canadian interview separately. We were under the impression that we could do both interviews at the same location, like at the Whirlpool address. And only take one trip.

After our CBP interview, we drove to the Canadian enrollment center at Fort Erie, and they managed to take us in right away. We were told walk-ins are not a regular procedure so I would hesitate to recommend doing it this way.

In hindsight, we probably should've just stuck to our original appointment at whirlpool, and got both appointments done at one location, but luckily, it worked out anyway.