There also a very important mental skill too. It’s not just learning to move your muscles precisely, correctly and in time. It’s also learning to hear and understand what you hear, to quickly identify what notes/chords/scales you’re hearing, what comes next, quickly generating a potentially good sounding melody and quickly understandibg of what notes it consists, what techniques need to be used to play it, where all its notes are on your instrument. Although this latter part probably cross-trains very very well between different instruments, but for a non-musician I expect it cannot be learned in 6 months.
There also a very important mental skill too. It’s not just learning to move your muscles precisely, correctly and in time. It’s also learning to hear and understand what you hear, to quickly identify what notes/chords/scales you’re hearing, what comes next, quickly generating a potentially good sounding melody and quickly understandibg of what notes it consists, what techniques need to be used to play it, where all its notes are on your instrument. Although this latter part probably cross-trains very very well between different instruments, but for a non-musician I expect it cannot be learned in 6 months.