tree-like keyword is innovative! also have some idea here.
so far best imo is like rust, U8 I32, but if one'd think they look ugly under global namespace, what about putting those under T., like T.U8?
also to note some, T.I8x16 for simd, T.F_1_8_7??? for some custom format like bfloat16 (since you mentioned fortran, haha)