I reached out to Northside to see if they could do anything with aging exposed aggregate concrete driveway. They replied same day and confirmed they would be out shortly to check it out. The next day I had a detailed quote that included power sweeping, two coats of sealant and added grit, for a price I found reasonable.
They came out the week after, right on time, and did as promised.
The outcome is spectacular, and several neighbours have asked about it. It really looks almost new!