yeah I did some diging and found those 2 topics
https://blenderartists.org/t/baking-animations-down-to-the-mesh-bones/692991https://blenderartists.org/t/how-to-bake-an-armature-animation/456771/5
The simplest solution is to export as fpx rather then gltf, because fpx has a “baked animation” setting in the exporter.