We’ve built a similar pipeline architecture for our product. One key thing I’ll mention is that we’re using Shaka-streamer which is a python wrapper around Shaka-packager (which in turn is a wrapper around ffmpeg). We queue our transcode jobs into a redis queue, and use k8s to scale the transcode workers based on queue volume. Lastly, as a few folks have mentioned, we have an experimental on-prem transcoding cluster with consumer grade HW that is pretty cheap.

If you’re interested in working on transcoding I’d highly recommend taking a look at Shaka-packager/streamer.