Specs for most of them are available, so we know they don't add new commands. They are just not a part of the official registry.
`GL_ATI_texture_compression_3dc` has no spec. `GL_APPLE_packed_pixels` had a unofficial one but it's now difficult to find, all the tokens it defines are also already defined in OpenGL 1.2, so I don't think exposing it is going to make any difference. The same reasoning as above wrt platform extensions applies for it as well.
It is part of the extension strings exposed by Mesa. In any case, we could filter it if there is an actual benefit, but I do not see why we would need to. What exactly looks wrong to you?
GLSL extensions aren't supposed to be exposed there, unless they have a matching GL extension to add tokens / commands or change GL behavior. This one doesn't do any of that on the GL side, and I believe it is not meant to be exposed in GL_EXTENSIONS. This leaves `GL_EXT_texture_edge_clamp` / `GL_EXT_texture_rectangle` / `GL_MESA_texture_signed_rgba` with unofficial specs and which we can expose, yes. And then there are more spec-less extensions that are exposed by native drivers. -- https://gitlab.winehq.org/wine/wine/-/merge_requests/10349#note_133537