Has anyone seen Open Calais [1]? It does tagging and categorization. It's been around for years and seems pretty powerful. It's a bit lower-level than Algorithmia (not href aware), but it seems more powerful, and a system like Algorithmia could be built on it.
The city does seem to be doing what it can to encourage and help providers, but I don't think they are willing to invest capital. Not sure whether or not that is a dealbreaker.
https://arxiv.org/abs/2209.15125