I have slowly googling, reading,checking shaders trying to learn by-the-metal how much can i load all space sim ships models in gpu memory (buffer?buffers? textures to hold data structures) and only send per frame 2 vec4 our pos and orientation?

Trying to learn in simple and direct understanding if its feasible?

Im pretty new in opengl (learned about shaders in directx when they first come out).. so many years till i grasped that book but never coded as was too busy in my official job.
So 6 months ago i restarted and focusing in opengl.. trying to understand the basics by-the-metal (i started as a machine code/assembler on the 80s and 90s just for you my opengl knowledge fellows to see how low level am i interested in learning exotic performant way to achieve this long time idea of store all/most 3d models in gpu and only stream our pos+orientation.

extra: seems in open gl we can only attach one buffer at a time if 1 specific type (flagging read only, stream or write).. simple doubt on this concept.. does this mean all re-assigning buffer A or buffer B to same attach/buffer type can only be done in Cpu side ? How can a shader only play with only gpu memory (multiple buffers and hack using 3d structures as way to store multi dimensional data structures)? Thanks