From my experience, the absolute magicians in fixed point math were the 8-bit and 16-bit video game designers. I was in awe of the optimizations they did. They made it possible to calculate 3D matrix maths in real time, for example, in order to make the first flight simulators and first person shooter games.
I see your point, but I have to believe there is a commercial path that can be mindfully pursued. You can build hosted tools, or add commercial value with an "app" model where there is a clear division between the platform, which is free, and the apps, which can be paid or not.
For example, an open source "community edition" could be treated as a freemium product and an OSS marketing could adapt a PLG playbook to help identify and nurture those who are good candidates for the "enterprise edition". Also, you have a community. They're in Slack or Discord, making pull requests, filing Github issues. You should be able to adapt the CLG playbook to help identify and nurture future customers from within the community.
The ffmpeg streaming model might do wonders for mobile battery life. I've been told that specialized video decoding chips are a lot less energy intensive than other types of client side rendering.
