I have a bunch of machines that only support DX9/GL2.1/GLES2.0/WebGL1 that I'd like to target. I'm currently using Unity for that.
Unfortunately those APIs are pretty ancient. Even if Bevy were to provide a renderer targeting those, it would end up being _much_ more limited. DX11/GLES 3/WebGL 2 are already pretty limited targets.
We simply don't have the contributors to create and maintain such a renderer, at least at the moment.
What is your use case for needing webgl1?
Bevy is also extremely modular. If you absolutely need webgl1 support, you can implement it yourself as a plugin without losing the rest of the non-rendering parts of bevy like audio, input, the core ECS of course, etc.