These are some good niches. As John mentioned above, you will run into licensing issues, and in the case of Medical Waste Disposal, there are environmental laws and standards to follow too, that might cause massive issues in daily operations/Due Dilligence if the target company has not been following them. We had a local case in Chicago where a medical device cleaning company was found to be in violation of Clean Air Act standards (I believe), and it was a massive thing.

If you would like some help with off market deal sourcing, let me know too, I run a buy-side business development company that helps with research and outreach. Here is our website: withcurators.com

Bumping this post! Im currently looking into Optometry - there seems to be a ton of small practices for sale. Would love to hear about other provider / services niches searchers are looking into.