I would like to suggest support for PipelineDB as it has a really nice synergy with TimescaleDB.
TimescaleDB is really good at ingesting data but it lacks some important functionality when it comes to aggregating it. That's where PipelineDB comes in as it is able to do real-time aggregation incrementally.
Even the developers of both plugins have talked about that synergy (https://github.com/pipelinedb/pipelinedb/issues/1876#issuecomment-337046226).
Pipelines that need fast data ingest and automatic data aggregation benefit a lot from using TimescaleDB in conjunction with PipelineDB. Personally, the lack of support for PipelineDB is a big deal-breaker for my current project as it would prevent me from being able to use DigitalOcean's DBaaS and make me resort to a normal droplet.