I think this is great, except I feel odd that it's just hanging around on the Deno global instead of being e.g. imported like any other database client.

    import KV from "https://deno.land/kv" // for example

If their protocol is indeed open and usable with your own backend, then that library should be able to work for anyone. And if they need some fancy native performance then maybe they could intercept that import when running code on Deno Deploy?

Treating their hosted service as "part of the runtime" which is what the Deno global tends to be for is the only remaining ick factor for me.