Could also check out the Auto Rig Pro ( https://artell.gumroad.com/l/auto-rig-pro ) plugin in Blender, as it does corrective shape-keys and makes exports to Unity/Unreal trivial. Also, FaceIt ( https://faceit-doc.readthedocs.io/en/latest/ ) uses the iPhone Lidar with the Unreal App, and makes facial expression capture less buggy.

Keep in mind most motion capture files are considered live-performances, and must be licensed by the original rights holders:

https://www.mocapclub.com/Pages/Library.htm

https://github.com/MattiasFredriksson/io_anim_c3d/releases

This project sort of works for basic mocap (calibration needs ChArUco board):

https://freemocap.org/

Or if you have the resources and athletic actors around:

https://www.rokoko.com/

Or for student projects could try:

https://www.mixamo.com/

Hope you make something awesome and fun =3