Can you say more about the requirements, and your authoring workflow?
This isn’t easy to do, see [Solved] Question about exporting skin Weights/Indices with Blender glTF-exporter for some discussion and ideas. Are you mainly concerned about downloading large amounts of data upfront? And are the number of animations such that you could export them all into one file (for later splitting/processing), or too much for even that? Or do you need to let artists create animations for the same characters while working in parallel on different files?