Beginner need help: should i install SD in external drive for Macbook air M2?

[fosall]

Hi, I am a beginner for using SD, i am not sure if i should install SD on my macbook air or my external drive.

macbook air m2, 8gb+256gb, external drive: 1tb.
i heard that for better performance, i should install the macOS system on my external drive, coz every software will run on the drive where the system is, but i am not sure about this.
also, are my devices enough for using SD?

thanks a lot in advance!

[fosall]

btw, my drive speed is max. 2800m/s