So there are two feature requests here: EXIF preservation and Colorspace preservation.
EXIF Preservation
It should be possible to make composer media optimization image enabled work without strip image metadata. We extract EXIF early in the pipeline and re-insert it on the end of it. That said I have found zero supported libraries to read and write EXIF easily in either JS or WASM. If someone fancies trying their hand on using the abandoned GitHub - hMatoba/piexifjs: Read and modify exif in client-side or server-side JavaScript. or trying to wasmify GitHub - paolobarbolini/img-parts: Low level crate for reading and writing Jpeg, Png and RIFF image containers I can only say pr-welcome .
Color Space
We use Canvas to convert the decoded image into a RGBA array. Canvas colorspace support is complicated. There is a WICG proposal to add support for fancier colorspaces but it’s not coming anytime soon.