[enkimute]

Take a look at Klein : https://www.jeremyong.com/klein/ (arm implementation is coming)

Its geometric product between motors is the equivalent of the 4x4 matrix product.

Although the basic computational complexity tells the story :

4x4 matrix product : 16 floats storage, 64 multiplies, 48 additions.

3D PGA versor product : 8 floats storage, 48 multiplies, 40 additions.