Greetings!
That, I’m afraid, I don’t know–I don’t really use the gltf pipeline.
Doing a forum-search, it looks like I asked something similar myself, once. At the time, one of the answers that I got was as follows:
So it looks like the answer–at least as of 2021–was to specifically export with blend2bam, and to use the extensions listed there.
As I don’t really use blend2bam, I don’t myself know how that’s done–but perhaps another forum-member will!