Interesting! Have you considered reaching out to one of those (e.g. Citymapper) and see if they would like to work with you? Either employ you, subcontract you, use you as an API, or whatever! :)

I think it's really cool that you maintain such a service and maybe they can find in you a good partnership!

I tried with Moovit, but they weren't interested unless the Agency was formerly part of it. At the time I was a board member on the citizens' board which was an official board of the agency, but still didn't have enough sway. The reality is that most transit smaller agencies are so under funded and under staffed, they just don't have the resources. Your lucky if there is more than one planner and a single technical person in many of these agencies.

I was the original person to create GTFS data (before real time tracking data existed, just stops, routes, and schedules) for my transit agency back in the mid 2000s, but again, Google wouldn't accept them unless they had signed agreements with the transit Agency. So at that time, I hosted my own Open Trip Planner instance.

One more thing I'll point out, is that I am reusing data that already exists for my apps. Most agencies are recognizing how important it is to have a GPS tracker on every bus. In some cases, it isn't for the rider, but is more for the agency to plan and keep track performance.

So, I am not the source of truth, which means any 3rd party app should really be getting their data from the original vendor. It is just a shame that many of these smaller vendors want to keep the data to themselves, and aren't willing to have public GTFS-rt data or data that other commercial applications are willing to use.