@dansup @pixelfed I understand you are targeting mobile users mostly. How do you intend to offload transcoding to browser users?

More generally - most platforms transcode everything server side so that they can re-encode content again in newer profiles or codecs as needed, to validate uploads (everything is transcoded to common profiles) and to improve quality/space tradeoff (mobile encoders tend to be really poor).
But that means server bills, of course.