Also, I see that SpiceDB has some telemetry (https://github.com/authzed/spicedb/blob/main/TELEMETRY.md) but I'm curious why it uses Prometheus Remote Write instead of allowing Prometheus scraping? Or are both supported?

the telemetry is written back to an endpoint in AuthZed (with just the limited data that doc describes), which is why it's remote write there is a standard prometheus endpoint with metrics that you can scrape for everyday monitoring

Ahhhh, so that's telemetry that you're collecting from OSS installs, that makes sense! Very clever scheme